#define _USE_MATH_DEFINES
#include <stdio.h>
#include <iostream>
using namespace std;

bool safe(int, int, int, int);

struct Point {
	int x;
	int y;
};

Point now = { 0, 0 };
Point goal;
Point obst;

int main(int argc, char *argv[]) {
	std::ios::sync_with_stdio(false);
	std::cin.tie(0);
	cin >> goal.x >> goal.y >> obst.x >> obst.y;
	int dirx;
	int diry;
	int flag;
	int cnt = 0;
	while (1) {
		dirx = goal.x - now.x; //dirx>0 で右に進むべき
		diry = goal.y - now.y; //diry>0 で左に進むべき
		flag = (abs(dirx) > abs(diry));
		if (dirx > 0) {
			if (diry > 0) { // 右上
				if (safe(now.x, now.y, dirx, diry)) {
					now.x++;
					now.y++;
				}
				else {
					now.x += flag;
					now.y += !flag;
				}
			}
			else if (diry < 0) { // 右下
				if (safe(now.x, now.y, dirx, diry)) {
					now.x++;
					now.y--;
				}
				else {
					now.x += flag;
					now.y += !flag;
				}
			}
			else if (diry == 0) { // 右
				now.x++;
			}
		}
		else if (dirx < 0) {
			if (diry > 0) { // 左上
				if (safe(now.x, now.y, dirx, diry)) {
					now.x--;
					now.y++;
				}
				else {
					now.x += flag;
					now.y += !flag;
				}
			}
			else if (diry < 0) { // 左下
				if (safe(now.x, now.y, dirx, diry)) {
					now.x--;
					now.y--;
				}
				else {
					now.x += flag;
					now.y += !flag;
				}
			}
			else if (diry == 0) { // 左
				now.x--;
			}
		}
		else if (dirx == 0) {
			if (diry > 0) { // 上
				now.y++;
			}
			else if (diry < 0) { // 下
				now.y--;
			}
			else if (diry == 0) { // 到着
				break;
			}
		}
		cnt++;
	}
	printf("%d\n", cnt);
	return 0;
}

bool safe(int nowx, int nowy, int dirx, int diry) {
	bool toRight = (dirx > 0);
	bool toLeft = !toRight;
	bool toUp = (diry > 0);
	bool toBottom = !toUp;
	bool safe;
	bool goalNext;
	if (toRight && toUp) {
		safe = !((nowx + 2 == obst.x) && (nowy + 2 == obst.y));
		goalNext = (now.x + 1 == goal.x) && (nowy + 1 == goal.y);
	}
	else if (toRight && toBottom) {
		safe = !((nowx + 2 == obst.x) && (nowy - 2 == obst.y));
		goalNext = (now.x + 1 == goal.x) && (nowy -1 == goal.y);
	}
	else if (toLeft && toUp) {
		safe = !((nowx - 2 == obst.x) && (nowy + 2 == obst.y));
		goalNext = (nowx - 1 == goal.x) && (nowy + 1 == goal.y);
	}
	else {
		safe = !((nowx - 2 == obst.x) && (nowy - 2 == obst.y));
		goalNext = (nowx - 1 == goal.x) && (nowy - 1 == goal.y);
	}
	return safe || goalNext;
}