#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int INF = 1e9;
int MOD = 1e9+7;
int cnt[100];
main(){
    int N;
    cin >> N;
    for(int i = 0;i < N;i++){
        for(int j = 0;j < N;j++){
            string s;
            cin >> s;
            if(s == "nyanpass")cnt[j]++;
        }
    }
    int no = -1;
    for(int i = 0;i < N;i++){
        if(cnt[i] != N-1)continue;
        if(no != -1){
            no = -1;
            break;
        }else no = i+1; 
    }
    cout << no << endl;
}