#include <bits/stdc++.h>
#include <atcoder/all>
#define ll long long
using namespace std;

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
    ll N;
    cin>>N;
    ll renncho=-1;
    vector<ll> cnt(N+1,0);
    for(int i=1;i<=N;++i){
        for(int j=1;j<=N;++j){
            string A;
            cin>>A;
            if(A=="nyanpass")cnt[j]++;
        }
    }
    for(int i=1;i<=N;++i){
        if(cnt[i]==N-1){
            if(renncho!=-1){cout<<-1<<endl;return 0;}
            else renncho=i;
        }
    }
    cout<<renncho<<endl;
}