#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int n;
    cin >> n;
    vector<vector<string>> a(n,vector<string>(n));
    for(int i = 0;i < n;i++){
        for(int j = 0;j < n;j++){
            cin >> a[i][j];
        }
    }
    int nyan = -1;
    for(int j = 0;j < n;j++){
        bool ans = true;
        for(int i = 0;i < n;i++){
            if(j == i)continue;
            if(a[i][j] != "nyanpass")ans = false;
        }
        if(ans && nyan == -1)nyan = j + 1;
        else if(ans && nyan != -1){
            nyan = -1;
            break;
        }
    }
    cout << nyan << endl;
    return 0;
}