import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt(sc.next());

        Set<Integer> renchon = new HashSet<>();
        for (int i = 0; i < N; i++) {
            for (int j = 0; j < N; j++) {
                String s = sc.next();
                if (s.equals("nyanpass")) renchon.add(j+1);
            }
        }

        if (renchon.size() > 1 || renchon.size() == 0) {
            System.out.println("-1");
        } else {
            renchon.forEach(System.out::println);
        }
    }
}