package m.shin;
import java.util.Scanner;
public class Con239 {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		int N = s.nextInt();
		int[] count = new int[N];
		for(int i = 0;i < N;i++){
			for(int k = 0;k < N;k++){
				if(s.next().equals("nyanpass")){
					count[k]++;
				}
			}
		}
		s.close();
		int ft = -1 , answer = -1;
		for(int i = 0;i < N;i++){
			if(count[i] == N-1 && ft == -1){
				ft = 1;
				answer = i+1;
			}else if(count[i] == N-1 && ft != -1){
				ft = 0;
			}
		}
		if(ft == 1){
			System.out.println(answer);
		}else{
			System.out.println(-1);
		}

	}

}