Language: C++

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
#define LLINF 9223372036854775807
#define MOD ll(1e9+7)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cerr<<#x<<": "<<x<<endl


int main(){
    int n;
    cin >> n;

    vector<vector<int>> a(n+1,vector<int>(n,0));
    for(int i = 0; i < n; i++){
        for(int j = 0; j < n-1; j++){
            cin >> a[i+1][j];
        }
    }

    vector<int> index(n+1,0);
    int endcnt = 0;
    int ans = 0;
    while(endcnt < n){
    bool impossible = true;
        ans++;
        vector<int> fight;
        for(int i = 1; i <= n; i++){
            int opponent = a[i][index[i]];
            //dbg(i);dbg(a[i][index[i]]);dbg(a[opponent][index[opponent]]);
            if(i == a[opponent][index[opponent]]){
                fight.insert(i);
            }
        }
        for(int i = 0; i < fight.size(); i++){
            impossible = false;
            index[fight[i]]++;
            if(index[fight[i]] == n-1){
                endcnt++;
            }
        }

        
        if(impossible){
            cout << -1 << endl;
            return 0;
        }
    }

    cout << ans << endl;
    return 0;

}


Compiler output:
a.cc: In function 'int main()':
a.cc:34:29: error: no matching function for call to 'std::vector<int>::insert(int&)'
   34 |                 fight.insert(i);
      |                 ~~~~~~~~~~~~^~~
In file included from /usr/include/c++/14/vector:66,
                 from /usr/include/c++/14/functional:64,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:53,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_vector.h:1484:9: note: candidate: 'template<class _InputIterator, class> std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, _InputIterator, _InputIterator) [with <template-parameter-2-2> = _InputIterator; _Tp = int; _Alloc = std::allocator<int>]'
 1484 |         insert(const_iterator __position, _InputIterator __first,
      |         ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1484:9: note:   candidate expects 3 arguments, 1 provided
In file included from /usr/include/c++/14/vector:72:
/usr/include/c++/14/bits/vector.tcc:133:5: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, const value_type&) [with _Tp = int; _Alloc = std::allocator<int>; iterator = std::vector<int>::iterator; const_iterator = std::vector<int>::const_iterator; value_type = int]'
  133 |     vector<_Tp, _Alloc>::
      |     ^~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/vector.tcc:133:5: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1395:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, value_type&&) [with _Tp = int; _Alloc = std::allocator<int>; iterator = std::vector<int>::iterator; const_iterator = std::vector<int>::const_iterator; value_type = int]'
 1395 |       insert(const_iterator __position, value_type&& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1395:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1413:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, std::initializer_list<_Tp>) [with _Tp = int; _Alloc = std::allocator<int>; iterator = std::vector<int>::iterator; const_iterator = std::vector<int>::const_iterator]'
 1413 |       insert(const_iterator __position, initializer_list<value_type> __l)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1413:7: note:   candidate expects 2 arguments, 1 provided
/usr/include/c++/14/bits/stl_vector.h:1439:7: note: candidate: 'std::vector<_Tp, _Alloc>::iterator std::vector<_Tp, _Alloc>::insert(const_iterator, size_type, const value_type&) [with _Tp = int; _Alloc = std::allocator<int>; iterator = std::vector<int>::iterator; const_iterator = std::vector<int>::const_iterator; size_type = long unsigned int; value_type = int]'
 1439 |       insert(const_iterator __position, size_type __n, const value_type& __x)
      |       ^~~~~~
/usr/include/c++/14/bits/stl_vector.h:1439:7: note:   candidate expects 3 arguments, 1 provided