RE是啥意思啊

#include <bits/stdc++.h>
using namespace std;
int arr[9][9];
int main()
{
	int n,i = 0,j = 0,shu = 1;
	cin >> n;
	while(shu < n * n){
		while(j <= n - 1 && arr[i][j] == 0){
			arr[i][j] = shu;
			j++;
			shu++;
		}
		j--;
		i++;
		while(j <= n - 1 && arr[i][j] == 0){
			arr[i][j] = shu;
			i++;
			shu++;
		}
		i--;
		j--;
		while(j > 0 && arr[i][j] == 0){
			arr[i][j] = shu;
			j--;
			shu++;
		}
		j--;
		i--;
		while(i > 0 && arr[i][j] == 0){
			arr[i][j] = shu;
			i--;
			shu++;	
		}
		i++;
		j++;
	}
	return 0;
}