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

int main()
{
int n;
cin >> n;
vector<vector<string>> v(n, vector<string>(n));
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
cin >> v[i][j];
}
}

int num = 0;
int man = -1;
for(int j = 0; j < n; j++){
bool ok = true;
for(int i = 0; i < n; i++){
if(i != j and v[i][j] != "nyanpass"){
ok = false;
}
}
if(ok){
num++;
man = j;
}
}
if(num == 1){
cout << man+1 << endl;
} else {
cout << -1 << endl;
}
return 0;
}