求看看代码哪里有问题

include<bits/stdc++.h>
using namespace std;
int main()
{
    string a,b;
    cin>>a;
    if(a.front()!='-'&&a.back()!='0')//”381“的情况 
    {
        reverse(a.begin(),a.end());
    }
    else if(a.front()=='-'&&a.back()!='0')//”-381“的情况 
    {
        a.erase(a.begin());
        reverse(a.begin(),a.end());
        a.insert(a.begin(),'-');
    }
    else if(a.front()!='-'&&a.back()=='0')//”380“
    {
        reverse(a.begin(),a.end());
        a.erase(a.front());
     } 
    else
    {
        a.erase(a.front());
        reverse(a.begin(),a.end());
        a.erase(a.front());
        a.insert(a.begin(),'-');

    }
    cout<<a;

    return 0;

 }