#include<iostream>
#include<cstring>
using namespace std;
struct date
{
	int x,y;
};
int n,m,x,y,g[410][410];
int nextp[12][2]={{-2,-1},{-2,1},{2,-1},{2,1},
				{-1,-2},{1,-2},{-1,2},{1,2},
				{-2,-2},{-2,2},{2,2},{2,-2}};
void bfs(int x,int y)
{
	memset(g,0,sizeof g);
	struct date a[40010];
	int head=1,tail=2;
	a[2].x=x,a[2].y=y;
	while(head<tail)
	{
		head++;
		for(int k=0;k<12;k++)
		{
			int tx=a[head].x+nextp[k][0];
			int ty=a[head].y+nextp[k][1];
			if(g[tx][ty]!=0||tx<1||ty<1)
				continue;
			tail++;
			g[tx][ty]=g[a[head].x][a[head].y]+1;
			if(tx==1&&ty==1)
			{
				cout<<g[tx][ty]<<endl;
				break;
				}	
			a[tail].x=tx;
			a[tail].y=ty;
		}
	}
}
int main()
{
	cin>>n>>m>>x>>y;
	bfs(n,m);
	bfs(x,y);
	return 0;
 }