#include <bits/stdc++.h>
using namespace std;
const double PI = acos(-1.0);
const int inf = 0x3f3f3f3f;
const long long mod = 1e9 + 7;
const int maxn = 1e6 + 5;
int a, b, c, d;
int main() {
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int x, y;
  if (a == c)
    x = 4;
  else
    x = (abs(a - c) + 1) * 2;
  if (b == d)
    y = 4;
  else
    y = (abs(b - d) + 1) * 2;
  int ans = x + y;
  printf("%d\n", ans);
  return 0;
}
