#include <bits/stdc++.h>
using namespace std;
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int a1 = abs(a - c) * 2;
  int b1 = abs(b - d) * 2;
  int ans = a1 + b1 + 4;
  if (a != c && b != d)
    printf("%d\n", ans);
  else
    printf("%d\n", ans + 2);
  return 0;
}
