#include <stdio.h>

int n, b[100];
char a[100][100][31];
char nya[] = "nyanpass";

int eq(char[], char[]);

int main(void) {
	scanf("%d", &n);
	int i, j;
	for(j = 0; j < n; j++) {
	for(i = 0; i < n; i++) {
		scanf("%s", a[i][j]);
	}
	}
	
	for(i = 0; i < n; i++) {
	for(j = 0; j < n; j++) {
		if(i == j) { continue; }
		if( ! eq(a[i][j], nya) ) {
			b[i] = 1;
			break;
		}
	}
	}
	
	int c = 0, p = -1;
	for(i = 0; i < n; i++) {
		if(b[i] == 0) {
			p = i + 1;
			c++;
		}
	}
	if(c != 1) { p = -1; }
	printf("%d\n", p);
	
	return 0;
}

int eq(char s[], char t[]) {
	int i = 0;
	while(s[i] == '\0' || t[i] == '\0') {
		if(s[i] != t[i]) { return 0; }
	}
	return (s[i] == t[i]);
}