chess

import java.util.Scanner;
 
 public class Main {

 	public static void main(String[] args) {
 		Scanner in = new Scanner(System.in);
 		int n = in.nextInt();
 		int sum = 0;
 		
 		int[][] board = new int[n][n];
 		String flag = "NIL";
 		
 		
 		for (int i = 0; i < n; i ++) {
 			for (int j = 0; j < n; j ++) {
 				board [i][j] = in.nextInt();
 			}
 		}
 		
 		for (int i = 0; i < n; i ++) {
 			sum = 0;
 			for (int j = 0; j < n; j ++) {
 				sum += board [i][j];
 				
 			}
 			if (sum == n ) {
 				flag = "X"; break; }
 			else if (sum == 0) {
 					flag = "O"; break; }
 			
 		}
 		
 for (int j = 0; j < n; j ++) {
 			sum = 0;
 			for (int i = 0; i < n; i ++) {
 				sum += board [i][j];
 				
 			}
 			if (sum == n ) {
 				flag = "X"; break; }
 			else if (sum == 0) {
 					flag = "O"; break; }
 		}

 {
 sum = 0;
 for (int k = 0; k < n; k ++)  {
 	sum += board[k][k];
 }

 if (sum == n ) {
 	flag = "X";  }
 else if (sum == 0 || sum == n) {
 		flag = "O";  }
 }
 	
 {
sum = 0;
 for (int k = 0; k < n; k ++)  {
 	sum += board[k][n-k-1];
 }

 if (sum == n ) {
 	flag = "X";  }
 else if (sum == 0 || sum == n) {
 		flag = "O";  }
 }
 		System.out.print(flag);
 	}	
 }