#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 = 1000 + 50;
int a, b, c, d;
int main() {
  while (~scanf("%d %d %d %d", &a, &b, &c, &d)) {
    int ans;
    if (a != c && b != d) {
      if (a < c && b < d) {
        ans = (abs(c - a) + 1 + abs(d - b) + 1) * 2;
      } else if (a > c && b > d) {
        ans = (abs(c - a) + 1 + abs(d - b) + 1) * 2;
      } else if (a > c && b < d) {
        ans = (abs(a + 1 - c) + abs(b - 1 - d)) * 2;
      } else {
        ans = (abs(c + 1 - a) + abs(d - 1 - b)) * 2;
      }
    } else {
      if (a == c && b != d) {
        ans = (abs(b - d) + 1) * 2 + 4;
      } else {
        ans = (abs(c - a) + 1) * 2 + 4;
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}
