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

public class Main {
	
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		final int N = sc.nextInt();
		
		String[][] data = new String[N][N];
		for(int i = 0; i < N; i++){
			for(int j = 0; j < N; j++){
				data[i][j] = sc.next();
			}
		}
		
		int count = 0, number = 0;
		LOOP:
		for(int j = 0; j < N; j++){
			for(int i = 0; i < N; i++){
				if(!"-".equals(data[i][j]) && !"nyanpass".equals(data[i][j])){
					continue LOOP;
				}
			}
			
			number = j;
			count++;
		}
		
		System.out.println(count == 1 ? (number + 1) : -1);
		
	}
	
}