#include<stdio.h>
#include<string.h>
int count[100];
main(){
    int N;
    scanf("%d",&N);
    for(int i = 0;i < N;i++){
        for(int j = 0;j < N;j++){
            char str[31];
            scanf("%s",str);
            if(strcmp(str,"nyanpass")==0){count[j]++;}
        }
    }
    int num = -1;
    for(int i = 0;i < N;i++){
        if(count[i]==(N-1)){
            if(num == -1){
               num=i+1;
            }else{
                num = -1;
                break;
            }
        }
    }
    printf("%d\n",num);
}