import java.util.Scanner;
public class Yukicoder239 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt(), res = -1;
        int cnt[] = new int[n];
        for (int i = 0; i < n; i++) 
            for (int j = 0; j < n; j++) 
                if (sc.next().equals("nyanpass")) 
                    cnt[j]++;
        for (int j = 0; j < n; j++) {
            if (cnt[j] == n-1) {
                if (res == -1) {
                    res = j + 1;
                } else {
                    res = -1;
                    break;
                }
            }
        }
        System.out.println(res);
    }
}