#include<bits/stdc++.h>
#define INF 987654321
#define UP 0
#define RIGHT 1
#define DOWN 2
#define LEFT 3
using namespace std;

int Y, X, board[9][9];
int dy[] = { -1,0,1,0 };
int dx[] = { 0,1,0,-1 };
int ans;
vector<pair<int, int> > listCCTV;

void check(int y, int x, int dir,int idx) {
    if (dir == UP) {
        for (int i = y - 1; i >= 0 ; i--) {
            if (board[i][x] == 6 )
                break;
            else if ((1 <= board[i][x] && board[i][x] <= 5) || board[i][x] >= 7)
                continue;

            board[i][x] = idx+7;
        }
    }
    else if (dir == RIGHT) {
        for (int i = x + 1; i < X; i++) {
            if (board[y][i] == 6 )
                break;
            else if ((1 <= board[y][i] && board[y][i] <= 5) || board[y][i] >= 7)
                continue;

            board[y][i] = idx + 7;
        }
    }
    else if (dir == DOWN) {
        for (int i = y + 1; i < Y; i++) {
            if (board[i][x] == 6 )
                break;
            else if ((1 <= board[i][x] && board[i][x] <= 5) || board[i][x] >= 7)
                continue;

            board[i][x] = idx + 7;
        }
    }
    else if (dir == LEFT) {
        for (int i = x - 1; i >= 0; i--) {
            if (board[y][i] == 6 )
                break;
            else if ((1 <= board[y][i] && board[y][i] <= 5) || board[y][i] >= 7)
                continue;

            board[y][i] = idx + 7;
        }
    }
}
void uncheck(int y, int x, int dir, int idx) {
    if (dir == UP) {
        for (int i = y - 1; i >= 0; i--) {
            if (board[i][x] == 6)
                break;
            else if (1 <= board[i][x] && board[i][x] <= 5)
                continue;

            else if (board[i][x]==idx+7)
                board[i][x] = 0;
        }
    }
    else if (dir == RIGHT) {
        for (int i = x + 1; i < X; i++) {
            if (board[y][i] == 6)
                break;
            else if (1 <= board[y][i] && board[y][i] <= 5)
                continue;

            else if (board[y][i] == idx + 7)
                board[y][i] = 0;
        }
    }
    else if (dir == DOWN) {
        for (int i = y + 1; i < Y; i++) {
            if (board[i][x] == 6)
                break;
            else if (1 <= board[i][x] && board[i][x] <= 5)
                continue;
            else if (board[i][x] == idx + 7)
                board[i][x] = 0;
        }
    }
    else if (dir == LEFT) {
        for (int i = x - 1; i >= 0; i--) {
            if (board[y][i] == 6)
                break;
            else if (1 <= board[y][i] && board[y][i] <= 5)
                continue;

            else if (board[y][i] == idx + 7)
                board[y][i] = 0;
        }
    }
}

void solve(int idx) {
    if (idx == listCCTV.size()) {
        int ret = 0;
        for (int i = 0; i < Y; i++) {
            for (int j = 0; j < X; j++) {
                if (board[i][j] == 0) {
                    ret++;
                }
            }
        }
        if (ans > ret) {
            ans = ret;
        }
        return;
    }
    int y = listCCTV[idx].first;
    int x = listCCTV[idx].second;
    int numCCTV = board[y][x];

    for (int dir = 0; dir < 4; dir++) {
        if (numCCTV == 1) {
            check(y, x, dir,idx);
            solve(idx + 1);
            uncheck(y, x, dir, idx);
        }
        else if (numCCTV == 2) {
            check(y, x, dir, idx);
            check(y, x, (dir + 2) % 4, idx);
            solve(idx + 1);
            uncheck(y, x, dir, idx);
            uncheck(y, x, (dir + 2) % 4, idx);
        }
        else if (numCCTV == 3) {
            check(y, x, dir, idx);
            check(y, x, (dir + 1) % 4, idx);
            solve(idx + 1);
            uncheck(y, x, dir, idx);
            uncheck(y, x, (dir + 1) % 4, idx);
        }
        else if (numCCTV == 4) {
            check(y, x, dir, idx);
            check(y, x, (dir + 1) % 4, idx);
            check(y, x, (dir + 2) % 4, idx);
            solve(idx + 1);
            uncheck(y, x, dir, idx);
            uncheck(y, x, (dir + 1) % 4, idx);
            uncheck(y, x, (dir + 2) % 4, idx);
        }
        else if (numCCTV == 5) {
            check(y, x, dir, idx);
            check(y, x, (dir + 1) % 4, idx);
            check(y, x, (dir + 2) % 4, idx);
            check(y, x, (dir + 3) % 4, idx);
            solve(idx + 1);
            uncheck(y, x, dir, idx);
            uncheck(y, x, (dir + 1) % 4, idx);
            uncheck(y, x, (dir + 2) % 4, idx);
            uncheck(y, x, (dir + 3) % 4, idx);
        }
    }

}
int main() {
    scanf("%d %d", &Y, &X);
    ans = INF;
    for (int i = 0; i < Y; i++) {
        for (int j = 0; j < X; j++) {
            scanf("%d", &board[i][j]);
            if (board[i][j] != 6 && board[i][j] != 0)
                listCCTV.push_back(make_pair(i, j));
        }
    }
    solve(0);
    printf("%d\n",ans);
    return 0;
}