#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m, a;
  cin >> n >> m;
  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)) {
        cout << "2";
        return 0;
      }
    }
  }
  cout << "4";
}
