求助，这个编译报错我实在看不懂

#include<bits/stdc++.h>
using namespace std;
int m,mp[320][320],z,ans,T;
bool safe[320][320];
struct meteor{int t,x,y;};
meteor met[50020];
struct rec{int x,y;};
queue<rec> q;
int dir[4][2]={{1,0},{-1,0},{0,1},{0,-1}};

void bfs(){
    rec now;
    now.x=0;now.y=0;
    mp[0][0]=0;q.push(now);
    while(q.size()){
        now=q.front();q.pop();
        T=mp[now.x][now.y];
        while(T==met[z].t){
            mp[met[z].x][met[z].y]=-2;
            z++;
        }
        if(mp[now.x][now.y]==-1)continue;
        for(int i=0;i<4;i++){
            rec nxt;
            nxt.x=now.x+dir[i][0];
            nxt.y=now.y+dir[i][1];
            if(nxt.x<0||nxt.y<0||nxt.x>300||nxt.y>300)
                continue;
            if(mp[nxt.x][nxt.y]==-1){
                mp[nxt.x][nxt.y]=mp[now.x][now.y]+1;
                if(safe[nxt.x][nxt.y]){
                    ans=mp[nxt.x][nxt.y];
                    return;
                }
                q.push(nxt);
            } 
        }
    }
    return;
}

int main(){
    cin>>m;
    for(int i=0;i<=300;i++)
        for(int j=0;j<=300;j++){
            mp[i][j]=-1;
            safe[i][j]=1;
        }
    for(int i=0;i<m;i++){
        cin>>met[i].x>>met[i].y>>met[i].t;
        safe[met[i].x][met[i].y]=0;safe[met[i].x-1][met[i].y]=0;
        safe[met[i].x+1][met[i].y]=0;safe[met[i].x][met[i].y-1]=0;
        safe[met[i].x][met[i].y+1]=0;
    }
    sort(met,met+m);
    z=0;
    ans=-1;
    bfs();
    cout<<ans;
    return 0;
}

            In file included from /usr/include/c++/8/bits/stl_algobase.h:71,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/predefined_ops.h: In instantiation of ‘constexpr bool __gnu_cxx::__ops::_Iter_less_iter::operator()(_Iterator1, _Iterator2) const [with _Iterator1 = meteor*; _Iterator2 = meteor*]’:
/usr/include/c++/8/bits/stl_algo.h:1847:14:   required from ‘void std::__insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1885:25:   required from ‘void std::__final_insertion_sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1971:31:   required from ‘void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:4834:18:   required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = meteor*]’
/tmp/compiler_406oeoc_/src:55:16:   required from here
/usr/include/c++/8/bits/predefined_ops.h:43:23: 错误：no match for ‘operator<’ (operand types are ‘meteor’ and ‘meteor’)
       { return *__it1 < *__it2; }
                ~~~~~~~^~~~~~~~
In file included from /usr/include/c++/8/bits/stl_algobase.h:67,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/stl_iterator.h:892:5: 附注：candidate: ‘template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator<(const __gnu_cxx::__normal_iterator<_IteratorL, _Container>&, const __gnu_cxx::__normal_iterator<_IteratorR, _Container>&)’
     operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/8/bits/stl_iterator.h:892:5: 附注：  template argument deduction/substitution failed:
In file included from /usr/include/c++/8/bits/stl_algobase.h:71,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/predefined_ops.h:43:23: 附注：  ‘meteor’ is not derived from ‘const __gnu_cxx::__normal_iterator<_IteratorL, _Container>’
       { return *__it1 < *__it2; }
                ~~~~~~~^~~~~~~~
In file included from /usr/include/c++/8/bits/stl_algobase.h:67,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/stl_iterator.h:899:5: 附注：candidate: ‘template<class _Iterator, class _Container> bool __gnu_cxx::operator<(const __gnu_cxx::__normal_iterator<_Iterator, _Container>&, const __gnu_cxx::__normal_iterator<_Iterator, _Container>&)’
     operator<(const __normal_iterator<_Iterator, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/8/bits/stl_iterator.h:899:5: 附注：  template argument deduction/substitution failed:
In file included from /usr/include/c++/8/bits/stl_algobase.h:71,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/predefined_ops.h:43:23: 附注：  ‘meteor’ is not derived from ‘const __gnu_cxx::__normal_iterator<_Iterator, _Container>’
       { return *__it1 < *__it2; }
                ~~~~~~~^~~~~~~~
/usr/include/c++/8/bits/predefined_ops.h: In instantiation of ‘bool __gnu_cxx::__ops::_Iter_less_val::operator()(_Iterator, _Value&) const [with _Iterator = meteor*; _Value = meteor]’:
/usr/include/c++/8/bits/stl_heap.h:133:48:   required from ‘void std::__push_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare&) [with _RandomAccessIterator = meteor*; _Distance = long int; _Tp = meteor; _Compare = __gnu_cxx::__ops::_Iter_less_val]’
/usr/include/c++/8/bits/stl_heap.h:237:23:   required from ‘void std::__adjust_heap(_RandomAccessIterator, _Distance, _Distance, _Tp, _Compare) [with _RandomAccessIterator = meteor*; _Distance = long int; _Tp = meteor; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_heap.h:342:22:   required from ‘void std::__make_heap(_RandomAccessIterator, _RandomAccessIterator, _Compare&) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1672:23:   required from ‘void std::__heap_select(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1933:25:   required from ‘void std::__partial_sort(_RandomAccessIterator, _RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1948:27:   required from ‘void std::__introsort_loop(_RandomAccessIterator, _RandomAccessIterator, _Size, _Compare) [with _RandomAccessIterator = meteor*; _Size = long int; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:1968:25:   required from ‘void std::__sort(_RandomAccessIterator, _RandomAccessIterator, _Compare) [with _RandomAccessIterator = meteor*; _Compare = __gnu_cxx::__ops::_Iter_less_iter]’
/usr/include/c++/8/bits/stl_algo.h:4834:18:   required from ‘void std::sort(_RAIter, _RAIter) [with _RAIter = meteor*]’
/tmp/compiler_406oeoc_/src:55:16:   required from here
/usr/include/c++/8/bits/predefined_ops.h:65:22: 错误：no match for ‘operator<’ (operand types are ‘meteor’ and ‘meteor’)
       { return *__it < __val; }
                ~~~~~~^~~~~~~
In file included from /usr/include/c++/8/bits/stl_algobase.h:67,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/stl_iterator.h:892:5: 附注：candidate: ‘template<class _IteratorL, class _IteratorR, class _Container> bool __gnu_cxx::operator<(const __gnu_cxx::__normal_iterator<_IteratorL, _Container>&, const __gnu_cxx::__normal_iterator<_IteratorR, _Container>&)’
     operator<(const __normal_iterator<_IteratorL, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/8/bits/stl_iterator.h:892:5: 附注：  template argument deduction/substitution failed:
In file included from /usr/include/c++/8/bits/stl_algobase.h:71,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/predefined_ops.h:65:22: 附注：  ‘meteor’ is not derived from ‘const __gnu_cxx::__normal_iterator<_IteratorL, _Container>’
       { return *__it < __val; }
                ~~~~~~^~~~~~~
In file included from /usr/include/c++/8/bits/stl_algobase.h:67,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from /usr/include/c++/8/ios:40,
                 from /usr/include/c++/8/istream:38,
                 from /usr/include/c++/8/sstream:38,
                 from /usr/include/c++/8/complex:45,
                 from /usr/include/c++/8/ccomplex:39,
                 from /usr/include/x86_64-linux-gnu/c++/8/bits/stdc++.h:52,
                 from /tmp/compiler_406oeoc_/src:1:
/usr/include/c++/8/bits/stl_iterator.h:899:5: 附注：candidate: ‘template<class _Iterator, class _Container> bool __gnu_cxx::operator<(const __gnu_cxx::__normal_iterator<_Iterator, _Container>&, const __gnu_cxx::__normal_iterator<_Iterator, _Container>&)’
     operator<(const __normal_iterator<_Iterator, _Container>& __lhs,
     ^~~~~~~~
/usr/include/c++/8/bits/stl_iterator.h:899:5: 附注：  template argument deduction/substitution failed:
In file included from /usr/include/c++/8/bits/stl_algobase.h:71,
                 from /usr/include/c++/8/bits/char_traits.h:39,
                 from 
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