import java.util.*;

public class Main{
    public static void main(String[] args){
        int i,j,poi = 0;
        Scanner sc = new Scanner(System.in);
        int num = sc.nextInt();
        int[] count = new int[num];
        String[][] line = new String[num][num];
        for(i=0;i<num;i++){
            for(j=0;j<num;j++){
                line[i][j] = sc.next();
            }
        }
        for(j=0;j<num;j++){
            for(i=0;i<num;i++){
                if(i==j && line[i][j].equals("-"))count[j]++;
                else if(line[i][j].equals("nyanpass"))count[j]++;
            }
            if(count[j] == num)poi++;
        }
        if(poi == 1){
            for(i=0;i<num;i++)
                if(count[i] == num)System.out.println(i+1);
        }
        else System.out.println("-1"); 
    }
}