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

void main(void){
    int n;
    scanf("%d",&n);
    int greetingList[100] = {};
    //int *greetingList = (int *)calloc(n,sizeof(int));
    for(int i = 0 ; i < n ; i ++){
        for(int j = 0 ; j < n ; j++){
            char greeting[100] = "a";
            scanf("%s",greeting);
            if(strcmp(greeting,"nyanpass") == 0){
                //(greetingList+j) = (greetingList+j) + 1;
                greetingList[j]++;
            }
        }
    }
    int particular = 0,count = 0;
    for(int i = 0 ; i < n ; i++){
        if(greetingList[i] == n-1){
            particular = i+1;
            count++;
        }
        if(count > 1){
            break;
        }
    }
    if(count == 1){
        printf("%d",particular);
    }else{
        printf("-1");
    }
}