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