/**************************************************************
    Problem: 1193
    User: lxy8584099
    Language: C++
    Result: Accepted
    Time:24 ms
    Memory:820 kb
****************************************************************/
 
/*
    贪心 吧两点走进到50之内吧
    然后50之内 bfs 打个表、、、 
*/
#include <cmath>
#include <cstdio>
using namespace std;
 
int xp,yp,xs,ys,ans,m[100]={0,3,2,3,2,3,4,5,4,5,6,3,2,1,2,3,4,3,4,5,6,5,2,1,4,3,2,3,4,5,4,5,6,3,2,3,2,3,4,3,4,5,6,5,2,3,2,3,4,3,4,5,4,5,6,3,4,3,4,3,4,5,4,5,6,5};
 
inline void swap(int &a,int &b) {int c=a; a=b; b=c;}
 
int main()
{
    scanf ("%d%d%d%d",&xp,&yp,&xs,&ys);
    if (xp>xs) swap(xp,xs);
    if (yp>ys) swap(yp,ys);//确保马在左下角
    if (xs-xp<6&&ys-yp<11) printf ("%d",m[(xs-xp)*11+ys-yp]);//如果可以直接贪心
    else while (1)
    {
        if (xp>xs) swap(xp,xs);
        if (yp>ys) swap(yp,ys);//确保马在左下角
        if (xs-xp<6&&ys-yp<11)//如果接近了
        {
            printf ("%d",ans+m[(xs-xp)*11+ys-yp]);
            return 0;
        }
        if (xp-xs>yp-ys) {xp+=1; yp+=2;}
        else {xp+=2; yp+=1;}//贪心
        ++ans;
    }
    return 0;
}