package yukicoder;

import java.util.Scanner;

public class yuki239 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner scan = new Scanner(System.in);
		int count = scan.nextInt();
		String[][] strArr = new String [count][count]; 
		int[][] intFlg = new int[count][count];
		int ans = 0;
		int ans3 = 0;

		Boolean ans_flg = false;
		
		for (int i = 0; i < count; i++) {
			for (int j = 0; j < count; j++) {
				strArr[i][j] = scan.next();
			}
		}
		
		for (int i = 0; i < count; i++) {
			for (int j = 0; j < count; j++) {
				
				if ("nyanpass".equals(strArr[j][i])){
					intFlg[i][j] = 3;
				} else if("-".equals(strArr[j][i]) ){
					intFlg[i][j] = 2;
				} else{
					intFlg[i][j] = 1;
				}
			}			
		}
		
		for (int i = 0; i < count; i++) {
						
			for (int j = 0; j < count; j++) {				
			
				if(intFlg[i][j] == 3){
					ans += 3;
				} else if (intFlg[i][j] == 2){
					ans += 2;
				} else {
					ans = -1;
				}
			}
			
			if(ans >= 7 && ans_flg == false){
				ans3 = i + 1;
				ans_flg = true;
			} else if(ans >= 7 && ans_flg == true){
				ans3 = -1;
				break;
			}			
			ans = 0;
			
		}
		if(ans_flg == true){
			System.out.print(ans3);
		}else {
			System.out.print(-1);
		}
		scan.close();

	}

}