红色海洋中的绿点

#include <bits/stdc++.h>
using namespace std;
int a[20][20],w[20][20];
bool check(int xa, int ya, int xb, int yb) {
	int a[2] = {0, 0};
	for (int i = xa; i <= xb; i++) {
		for (int j = ya; j <= yb; j++){
            a[w[i][j]]++;
        }
	}
	return a[0] == a[1];
}
int main(){
    int n,m;
    cin>>n>>m;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            cin>>a[i][j];
        }
    }
    int ans = 0;
    for (int i = 1; i <= n; i++) {
    	for (int j = 1; j <= m; j++) {
    		for (int ii = i; ii <= n; ii++) {
    			for (int jj = j; jj <= m; jj++) {
    				if (check(i, j, ii, jj))ans = max(ans, (ii - i + 1) * (jj - j + 1));
    			}
    		}
    	}
    }
    cout << ans << endl;
    return 0;
}