10074.cpp

#include <bits/stdc++.h>

using namespace std;

int main()
{
	int m, n, v, field[101][101];
	while (scanf("%d%d", &m,&n) != EOF)
	{
		if (m == 0 && n == 0)
		{
			break;
		}
		int best = 0;
		for (int i = 0; i < m; i++)
		{
			for (int j = 0; j < n; j++)
			{
				cin >> v;
				if (j == 0)
				{
					if (v == 0)
					{
						field[i][j] = 1;
						if (field[i][j] > best)
						{
							best = field[i][j];
						}
					}
					else
					{
						field[i][j] = 0;
					}
				}
				else
				{
					if (v == 0)
					{
						field[i][j] = field[i][j - 1] + 1;
						if (field[i][j] > best)
						{
							best = field[i][j];
						}
					}
					else
					{
						field[i][j] = 0;
					}
				}
			}
		}
		for (int i = 0; i < m; i++)
		{
			for (int j = 0; j < n; j++)
			{
				if (field[i][j] > 0)
				{
					int rows = 1;
					int cols = field[i][j];
					for (int k = i + 1; k < m; k++)
					{
						if (field[k][j] == 0)
						{
							break;
						}
						cols = min(cols, field[k][j]);
						rows++;
						if (rows * cols > best)
						{
							best = rows * cols;
						}
					}
				}
			}
		}
		cout << best << endl;
	}
	return 0;
}