Tunnels

input/code.cpp: In function 'int main()':
input/code.cpp:14:19: error: '__gnu_cxx::__alloc_traits<std::allocator<std::pair<int, int> > >::value_type' has no member named 'f'
         inout[t1].f++;
                   ^
input/code.cpp:15:19: error: '__gnu_cxx::__alloc_traits<std::allocator<std::pair<int, int> > >::value_type' has no member named 's'
         inout[t2].s++;
                   ^
input/code.cpp:20:30: error: '__gnu_cxx::__alloc_traits<std::allocator<std::pair<int, int> > >::value_type' has no member named 'f'
         answ += abs(inout[i].f - inout[i].s);
                              ^
input/code.cpp:20:43: error: '__gnu_cxx::__alloc_traits<std::allocator<std::pair<int, int> > >::value_type' has no member named 's'
         answ += abs(inout[i].f - inout[i].s);
                                           ^

#include <bits/stdc++.h>

using namespace::std;

ifstream fin("input.txt");

int main()
{
    int n, m, t1, t2;
    cin >> n >> m;
    vector<pair<int, int> > inout(n + 1);
    for (int i = 0; i < m; i++) {
        cin >> t1 >> t2;
        inout[t1].f++;
        inout[t2].s++;
    }

    int answ = 0;
    for (int i = 1; i <= n; i++) {
        answ += abs(inout[i].f - inout[i].s);
    }
    answ /= 2;

    cout << answ << "\n";
}