#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, m;
  scanf("%d%d", &n, &m);
  int ans = 4;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < m; j++) {
      int x;
      scanf("%d", &x);
      if (x == 1 && (i == 0 || i == n - 1 || j == 0 || j == m - 1)) ans = 2;
    }
  printf("%d", ans);
  return 0;
}
