#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main(void) {
	int n;
	cin >> n;
	vector<int> candidates(n, 1);
	string s;
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < n; ++j) {
			cin >> s;
			if (s != "nyanpass" && s != "-")
				candidates[j] = 0;
		}
	}
	int id = 0;
	for (int i = 0; i < n; ++i)
		if (candidates[i] == 1) id = i + 1;
	int renchon = count(candidates.begin(), candidates.end(), 1);
	if (renchon == 1) cout << id << endl;
	else cout << -1 << endl;
	return 0;
}