#include <stdio.h>
#include <algorithm>
#include <deque>
using namespace std;
using ll = long long;

int main() {
	char A[31], Sample[] = "nyanpass";
	int n, Match[100] = { 0 };
	scanf("%d", &n);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < n; j++) {
			scanf("%s", A);
			if (i == j)
				continue;
			bool str_match = true;
			for (int i = 0; i < 9; i++)
				str_match &= A[i] == Sample[i];
			Match[j] += str_match;
		}
	}

	int match_id, match_count = 0;
	for (int i = 0; i < n; i++)
		if (Match[i] == n - 1)
			match_count++, match_id = i;
	if (match_count != 1)
		printf("-1\n");
	else
		printf("%d\n", match_id + 1);
}