#include <bits/stdc++.h>
using namespace std;
int n, m;
int main() {
  cin >> n >> m;
  bool flg = false;
  int a;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      cin >> a;
      if (a == 1 && (i == 0 || i == n - 1 || j == 0 || j == m - 1)) flg = true;
    }
  if (flg)
    cout << 2 << endl;
  else
    cout << 4 << endl;
  return 0;
}
