#include<bits/stdc++.h>
#define rep(i,a,n) for (int i = a;i < n;i++)
#define per(i,n,a) for (int i = n-1;i >= a;i--)
using namespace std;

int main() {
    int a[110] = {}, i, j, n, f = 0;
    char x[40];
    scanf("%d", &n);
    rep(i, 0, n) {
        rep(j, 1, n + 1) {
            scanf("%s", x);
            if (strcmp(x, "nyanpass") == 0)a[j]++;
        }
    }
    rep(i, 1, 100 + 1) {
        if (a[i] == n - 1)f = f ? -1 : i;
    }
    printf("%d",f?f:-1);
    return 0;
}