#include <stdio.h>
#include <string.h>

int main() {
	char a[100][100][31];
	int n, cnt[100] = {}, cnt2 = 0, renge, i, j;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		for (j = 0; j < n; j++) {
			scanf("%s", a[i][j]);
			if (strcmp(a[i][j], "nyanpass") == 0) {
				cnt[j]++;
			}
		}
	}

	for (i = 0; i < n; i++) {
		if (cnt[i] == n - 1) {
			cnt2++;
			renge = i + 1;
		}
	}

	if (cnt2 != 1) printf("-1\n");
	else printf("%d\n", renge);
	
	return 0;
}