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

int main(void){
	int i,j,n;
	char s[110][110];
	
	int rentyon = -1;
	scanf("%d", &n);
	
	for(i=1;i<=n;i++){
		for(j=1;j<=n;j++){
			char str[50];
			scanf("%s", str);
			if(strcmp(str, "nyanpass") == 0){
				s[i][j] = 1;
			}else{
				s[i][j] = 0;
			}
		}
	}
	
	for(j=1;j<=n;j++){
		int tmp = 0;
		for(i=1;i<=n;i++){
			tmp += s[i][j];
		}
		if(tmp == (n-1)){
			if(rentyon != -1){
				rentyon = -1;
				j=i=n;
				break;
			}else{
				rentyon = j;
			}
		}
	}
	
	printf("%d\n", rentyon);
	
	return 0;
}