#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000001

int main(){
	
	string nya = "nyanpass";
	
	int n;
	cin>>n;
	
	vector<vector<string>> s(n,vector<string>(n));
	rep(i,n){
		rep(j,n)cin>>s[i][j];
	}
	
	vector<int> ans;
	
	rep(i,n){
		bool f = true;
		rep(j,n){
			if(i==j)continue;
			if(s[j][i]!=nya)f = false;
		}
		if(f)ans.push_back(i);
	}
	
	if(ans.size()!=1)cout<<-1<<endl;
	else cout<<ans[0]+1<<endl;
	
	return 0;
}