import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		int n = sc.nextInt();
		int[] sonmin = new int[n];
		for (int i=0; i<n; i++) {
			for (int j=0; j<n; j++) {
				String temp = sc.next();
				if (temp.equals("nyanpass") || temp.equals("-")) {
					sonmin[j]++;
				}
			}
		}
		
		int ans = -1;
		int num = 0;
		for (int i=0; i<n; i++) {
			if (sonmin[i] == n) {
				ans = i;
				num++;
			}
		}
		System.out.println(num>=2?-1:ans+1);
		
	}
}