na982

#include <stdio.h>
#include <queue>
#include <algorithm>
using namespace std;

int n, m, ret;
int map[8][8];

const int dy[] = { -1, +1, 0, 0 };
const int dx[] = { 0, 0, -1, +1 };

void bfs() {
	queue<int> q;
	int backup[8][8];
	int visited[8][8] = { 0, };
	for (int y = 0; y < n; ++y) {
		for (int x = 0; x < m; ++x) {
			backup[y][x] = map[y][x];
			if (backup[y][x] == 2) {
				q.push(y * 10 + x);
				visited[y][x] = 1;
			}
		}
	}

	while (!q.empty()) {
		int cur = q.front();	q.pop();

		int cy = cur / 10;
		int cx = cur % 10;

		backup[cy][cx] = 2;

		for (int dir = 0; dir < 4; ++dir) {
			int ny = cy + dy[dir];
			int nx = cx + dx[dir];

			if (ny < 0 || ny >= n || nx < 0 || nx >= m) {
				continue;
			}

			if (visited[ny][nx] == 0 && backup[ny][nx] == 0) {
				visited[ny][nx] = 1;
				q.push(ny * 10 + nx);
			}
		}
	}

	int candi = 0;
	for (int y = 0; y < n; ++y) {
		for (int x = 0; x < m; ++x) {
			if (backup[y][x] == 0) {
				++candi;
			}
		}
	}

	if (ret < candi) {
		ret = candi;
	}
}

void pick_dfs(int count, int sy, int sx) {
	if (count == 3) {
		bfs();
		return;
	}

	for (int y = sy; y < n; ++y) {
		for (int x = sx; x < m; ++x) {
			if (map[y][x] == 0) {
				map[y][x] = 1;
				pick_dfs(count + 1, y, x);
				map[y][x] = 0;
			}
		}
		sx = 0;
	}
}

int main()
{
	scanf("%d %d", &n, &m);
	for (int y = 0; y < n; ++y) {
		for (int x = 0; x < m; ++x) {
			scanf("%d", &map[y][x]);
		}
	}

	pick_dfs(0, 0, 0);

	printf("%d\n", ret);

	return 0;
}