#include <bits/stdc++.h>
using namespace std;
int x, y, a, b, A[10];
int main() {
  scanf("%d%d", &x, &y);
  scanf("%d%d", &a, &b);
  A[1] = abs(x - (a - 1)) + abs(y - (b - 1));
  A[2] = abs(x - (a - 1)) + abs(y - (b + 1));
  A[3] = abs(x - (a + 1)) + abs(y - (b - 1));
  A[4] = abs(x - (a + 1)) + abs(y - (b + 1));
  sort(A + 1, A + 5);
  printf("%d\n", A[1] + A[2] + 6);
  return 0;
}
