#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, k, x = 4;
  ;
  cin >> n >> m;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      cin >> k;
      if (k == 1)
        if (i == 0 || i == n - 1 || j == 0 || j == m - 1) x = 2;
    }
  cout << x << endl;
}
