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