不知道什么数据让我程序wa，求数据

#include<bits/stdc++.h>
using namespace std;
const int N=2e5+6;
typedef long long ll;
ll n,m,a[N],b[N];
vector<int> c;
set<ll> s1[N],s2[N],s3,s4;
void solve()
{
  cin>>n>>m;
  ll cnt=0;
  for(int i=1;i<=m;++i) cin>>a[i];
  for(int k=1;k<=m;++k)
  {
    for(int i=1;i<=n;++i)
    { 
        if(a[k]>=n*i-n+1&&a[k]<=i*n) s1[i].insert(a[k]);
        if(a[k]==n*i-n+1) s2[i].insert(a[k]);
        if(a[k]==(n+1)*i-n) s3.insert(a[k]);
        if(a[k]==(n-1)*i+1) s4.insert(a[k]);
        if(s1[i].size()==n||s2[i].size()==n||s3.size()==n||s4.size()==n)
        {
            cout<<k<<endl;
            //cout<<s1[i].size()<<" "<<i<<endl;
            return;
        }
    }
  }
  //for(auto c:s1[3]) cout<<c<<" ";
  puts("-1");
  //cout<<cnt<<endl;
}
int main()
{
  int t=1;
  //cin>>t;
  while(t--)
  solve();
  return 0;
}