为什么会这样

提交后发现上面写着编译错误，可在devc++上运行的好好的啊

#include<bits/stdc++.h>
using namespace std;
int n, x1, y1, x2, y2;
vector<bitset<1005>> bs;
int vis[1005][1005];
complex<int> c1, c2;
complex<int> c[] = {complex<int>(1, 0), complex<int>(0, 1), complex<int>(-1, 0), complex<int>(0, -1)};
queue<complex<int>> q;
int main(){
    cin >> n;
    for(int i = 0; i < n; i++){
        string s;
        cin >> s;
        reverse(s.begin(), s.end());
        bitset<1005> bs1(s);
        bs.push_back(bs1);
    }cin >> x1 >> y1 >> x2 >> y2;
    x1--, y1--, x2--, y2--;
    c1 = complex<int>(x1, y1);
    c2 = complex<int>(x2, y2);
    q.push(c1);
    while(q.size()){
        complex<int> comp(q.front());
        int x = comp.real(), y = comp.imag();
        int k = vis[x][y] + 1;
        q.pop();
        for(complex<int> c3: c){
            complex<int> c4(comp + c3);
            int x1 = c4.real(), y1 = c4.imag();
            if(x1 < 0 or x1 > n or y1 < 0 or y1 > n or bs[x1][y1])
                continue;
            vis[x1][y1] = k;
            q.push(c4);
            if(q.back() == c2){
                cout << k;
                return 0;
            }
        }
    }
}