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

int main(){
	unsigned N; char ***A; // “ü—Í
	unsigned ren; // ÅŒã‚ÉŒ©‚‚¯‚½‚ê‚ñ‚¿‚å‚ñŒó•â
	unsigned countren; //‚ê‚ñ‚¿‚å‚ñŒó•â‚̐”
	unsigned countnyan; //‚É‚á‚ñ‚Ï‚·”
	unsigned i, j; // ƒJƒEƒ“ƒ^•Ï”

	scanf("%d", &N);
	A = (char ***)malloc(sizeof(char **) * N);
	for(i = 0; i < N; i++){
		A[i] = (char **)malloc(sizeof(char *) * N);
		for(j = 0; j < N; j++){
			A[i][j] = (char *)malloc(32);
			scanf("%s", A[i][j]);
		}
	}

	for(i = 0; i < N; i++){
		countnyan = 0; for(j = 0; j < N; j++) if(strcmp(A[j][i], "nyanpass")) countnyan++; //‘º–¯”ԍ†i”Ô‚ª‚É‚á‚ñ‚Ï‚·‚ÆŒ¾‚Á‚½‰ñ”‚𐔂¦‚é
		if(countnyan == N - 1){
			ren = i;
			countren++;
		}
	}
	if(countren == 1) printf("%d\n", ren + 1);
	else printf("-1\n");
}