#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;

int main(){
	char s[101][101][31]={};int n;scanf("%d",n); 
	int b[101];
	for(int i=0;i<n;i++)b[i]=-1;
	for(int i=0;i<n;i++)for(int j=0;j<n;j++){
		scanf("%s",s[i][j]);
		if(strcmp(s[i][j],"nyanpass")==0){
			if(b[i]<0||b[i]==1)b[i]=1;
			else b[i]=0;
		}
	}
	int ans=0,cnt=0; 
	for(int i=0;i<n;i++)if(b[i]==1){ans=i+1;cnt++;}
	if(cnt>1)printf("-1\n");
	else printf("%d\n",ans); 
	return 0;
}