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