import java.util.*;
class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String[][] list = new String[n][n];
		int sum = 0;
		int id  = -1;
		for(int i = 0; i < n; i++) {
			for(int j = 0; j < n; j++) {
				list[i][j] = sc.next();
			}
		}
		IN:for(int i = 0; i < n; i++) {
			for(int j = 0; j < n; j++) {
				if(i == j) continue;
				if(!list[j][i].equals("nyanpass")) continue IN;
			}
			sum++;
			id = i;
		}
		if(sum != 1) id = -2;
		System.out.println((id+1));
		
		
		
		
	}
}