#include <bits/stdc++.h>
void merge(int arr[], int l, int m, int r) {
  int i, j, k;
  int n1 = m - l + 1;
  int n2 = r - m;
  int L[n1], R[n2];
  for (i = 0; i < n1; i++) L[i] = arr[l + i];
  for (j = 0; j < n2; j++) R[j] = arr[m + 1 + j];
  i = 0;
  j = 0;
  k = l;
  while (i < n1 && j < n2) {
    if (L[i] <= R[j]) {
      arr[k] = L[i];
      i++;
    } else {
      arr[k] = R[j];
      j++;
    }
    k++;
  }
  while (i < n1) {
    arr[k] = L[i];
    i++;
    k++;
  }
  while (j < n2) {
    arr[k] = R[j];
    j++;
    k++;
  }
}
void mergeSort(int arr[], int l, int r) {
  if (l < r) {
    int m = l + (r - l) / 2;
    mergeSort(arr, l, m);
    mergeSort(arr, m + 1, r);
    merge(arr, l, m, r);
  }
}
int main() {
  int n, i = 0, k = 0, j = 0, count = 0, t = 0, m, c[200002], flag = 0,
         a[52][52], b[100000];
  scanf("%d %d", &n, &m);
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++) {
      scanf("%d", &a[i][j]);
      if (a[i][j] == 1) count++;
    }
  }
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++) {
      if ((i == 0 || i == n - 1 || j == 0 || j == m - 1) && (a[i][j] == 1)) {
        flag = 1;
      }
    }
  }
  if (flag == 1)
    printf("2");
  else if (flag == 0 && count > 1)
    printf("4");
  else if (flag == 0 && count == 1)
    printf("4");
  return 0;
}
