#include <bits/stdc++.h>
using namespace std;
#define X first
#define Y second

int dx[4] = {1,0,-1,0};
int dy[4] = {0,1,0,-1};
int n,m;
int board1[10][10];
int board2[10][10];
vector<pair<int,int>> cctv;

bool OOB(int a, int b){
  return a < 0 || a >= n || b < 0 || b >= m;
}

void upd(int x, int y, int dir){
  dir %= 4;
  while(1){
    x += dx[dir];
    y += dy[dir];
    if(OOB(x,y) || board2[x][y] == 6) return;
    if(board2[x][y] != 0) continue;
    board2[x][y] = 7;
  }
}

int main(void){
  ios::sync_with_stdio(0);
  cin.tie(0);
  cin >> n >> m;
  int mn = 0;
  for(int i = 0; i < n ; i++){
    for(int j = 0; j< m; j++){
      cin >> board1[i][j];
      if(board1[i][j] != 0 && board[i][j] != 6)
        cctv.push_back({i,j});
      if(board1[i][j] == 0) mn++;
    }
  }
  for(int tmp = 0; tmp < (1<<(2 * cctv.size())); tmp ++){

    for(int i = 0; i< n; i++)
      for(int j = 0; j< m ; j++)
        board2[i][j] = board1[i][j];
    int brute = tmp;
    for(int i = 0; i< cctv.size(); i++){
      int dir = brute % 4;
      brute /= 4;
      int x = cctv[i].X;
      int y = cctv[i].Y;
      if(board1[x][y] == 1){
        upd(x,y,dir);
      }
      else if(board1[x][y] == 2){
        upd(x,y,dir);
        upd(x,y,dir + 2);
      }
      else if(board1[x][y] == 3){
        upd(x,y,dir);
        upd(x,y,dir+1);
      }
      else if(board1[x][y] == 4){
        upd(x,y,dir);
        upd(x,y,dir+1);
        upd(x,y,dir+2);
      }
      else{
        upd(x,y,dir);
        upd(x,y,dir+1);
        upd(x,y,dir+2);
        upd(x,y,dir+3);
      }
    }
    int val = 0;
    for(int i = 0; i< n; i++)
      for(int j = 0; j< m ; j++)
          val += (board2[i][j] == 0);
    mn = min(mn,val);
  }
  cout << mn;
}