import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[][] a = new String[n][n];
		for(int i = 0 ; i < n ; i++) {
			for(int j = 0 ; j < n ; j++) {
				a[i][j] = sc.next();
			}
		}
		int ret = 0; int cnt1 = 0;
		for(int i = 0 ; i < n ; i++) {
			int cnt = 0;
			for(int j = 0 ; j < n ; j++) {
				if(a[j][i].equals("nyanpass")) {
					cnt++;
				}
				if(cnt == n - 1) {
					cnt1++;
					ret = i + 1;
					break;
				}
			}
		}
		if(cnt1 == 1) {
			System.out.println(ret);
		} else {
			System.out.println(-1);
		}
 	}
}