#include <bits/stdc++.h>
using namespace std;

int main()
{
	int N;
	cin >> N;
	vector<vector<string>> A( N, vector<string>( N ) );
	for( int i = 0; i < N; i++ ) {
		for( int j = 0; j < N; j++ ) {
			cin >> A[i][j];
		}
	}

	int idx;
	int cnt = 0;
	for( int j = 0; j < N; j++ ) {
		int flag = 0;
		for( int i = 0; i < N; i++ ) {
			if( i == j ) continue;
			if( A[i][j] != string( "nyanpass" ) ) flag = 1;
		}
		if( flag == 0 ) {
			idx = j;
			cnt++;
		}
	}
	int ans = -1;
	if( cnt == 1 ) ans = idx + 1;

	cout << ans << endl;
}