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