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