#include <stdio.h>
#include <algorithm>
#include <iostream>
#include <string>
#include <vector>
#include <functional>
#include <map>
#include <iomanip>
#include <math.h> 
#include <stack>
#include <queue>
#include <bitset>
#include <cstdlib>
#include <tuple>
#include <cctype>
#include <ctype.h>
#include <set>
#include <sstream>

using namespace std;


int main() {
	int i, j, k;
	vector<bool>flag(110, false);
	vector<vector<string>>list(111, vector<string>(111));
	int n;

	cin >> n;


	for (i = 0; i < n; i++) {
		for (j = 0; j < n; j++) {
			string s;
			cin >> s;
			list[i][j] = s;
		}
	}

	
	for (i = 0; i < n; i++) {
		for (j = 0; j < n; j++) {
	
			if (list[i][j] == "nyanpass") {

				bool fflag = false;

				for (k = 0; k < n; k++) {
					if (k == j) continue;

					if (list[k][j] != "nyanpass") {
						fflag = true;
						//flag[j] = true;
						break;
					}
				}
				if (fflag == false) {
					flag[j] = true;
				}
			}

		}
	}

	int cnt = 0;
	int ans;

	for (i = 0; i < n; i++) {
		if (flag[i] == true) {
			cnt++;
			ans = i + 1;
		}
	}

	if (cnt >= 2 || cnt == 0 ) {
		cout << -1 << endl;
	}
	else {
		cout << ans << endl;
	}





	getchar();
	getchar();
	return 0;
}