#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, num, ans;
  scanf("%d %d", &n, &m);
  ans = 4;
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < m; j++) {
      scanf("%d", &num);
      if ((i == 0 || i == n - 1 || j == 0 || j == m - 1) && num == 1) {
        ans = 2;
      }
    }
  }
  cout << ans << endl;
}
