#include <bits/stdc++.h>
using namespace std;
int main() {
  int sx, sy, dx, dy, difx, dify;
  cin >> sx >> sy >> dx >> dy;
  difx = abs(sx - dx) != 0 ? abs(sx - dx) + 1 : abs(sx - dx);
  dify = abs(sy - dy) != 0 ? abs(sy - dy) + 1 : abs(sy - dy);
  if (difx == dify) {
    cout << difx * 4 << endl;
  } else if (difx > dify) {
    cout << (difx * 4) - (dify != 0 ? (difx - dify) * 2 : (difx - 2) * 2)
         << endl;
  } else {
    cout << (dify * 4) - (difx != 0 ? (dify - difx) * 2 : (dify - 2) * 2)
         << endl;
  }
  return 0;
}
