#include<iostream>
#include<string>
#include<vector>

#define rep(i,n) for(i=0; i<n; i++)

using namespace std;

int main()
{
    int n;
    cin >> n;
    
    int i,j;
    vector<int> renchon(n,0);
    string s;
    rep(i,n) {
        rep(j,n) {
            cin >> s;
            if(s=="nyanpass") {
                renchon[j+1]++;
            }
        }
    }
    int specific=0;
    for(i=0;i<n;i++)if(renchon[i]==n-1)specific=specific?-1:i;
    cout << specific << endl;
    return 0;
}