package no239;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[][] m = new String[n][n];
		for(int i=0;i<n;i++) {
			for(int j=0;j<n;j++) {
				m[j][i] = sc.next();
			}
		}
		int renge = -1;
		for(int i=0;i<n;i++) {
			boolean flag = true;
			for(int j=0;j<n;j++) {
				if (i == j) {
					continue;
				}
				if (!m[i][j].equals("nyanpass")) {
					flag = false;
					break;
				}
			}
			if (flag) {
				if (renge == -1) {
					renge = i + 1;
				}else{
					renge = -1;
					break;
				}
			}
		}
		System.out.println(renge);
	}

}