#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
string a[300][300];
int main(){
int n;cin>>n;
rep(i,n)rep(j,n) cin>>a[i][j];
int cnt=0,m=-1;
rep(j,n) {
bool ok=1;
rep(i,n) if(a[i][j]!="nyanpass")ok=0;
if(ok)cnt++,m=j;
}
cout<<(cnt==1 ?m:-1) <<endl;
}