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

int main() {
	int N;
	cin >> N;

	vector<vector<string>> v(N, vector<string>(N));
	for (int i = 0; i < N; i++) {
		for (int j = 0; j < N; j++) {
			cin >> v.at(i).at(j);
		}
	}

	int c = 0,
		n = 0;
	for (int i = 0; i < N; i++) {
		if (c > 1) break;

		bool b = 1;
		for (int j = 0; j < N; j++) {
			string s = v.at(j).at(i);
			if (s == "-" || s == "nyanpass") {
				0; //NOP
			}
			else {
				b = 0;
				break;
			}
		}

		if (b) {
			n = i + 1;
			c++;
		}
	}

	if (c == 1) {
		cout << n << endl;
	}
	else {
		cout << -1 << endl;
	}
}