#include<bits/stdc++.h>
using namespace std;
int n,m,xa,ya;
int a[1005][1005],vis[1005][1005];
int d[12][2]= {{-2,1},{-1,2},{1,2},{2,1},{2,-1},{1,-2},{-1,-2},{-2,-1},{2,2},{2,-2},{-2,2},{-2,-2}};
struct node {
	int x;
	int y;
	int ans;
};
queue<node>q;
void bfs(int x,int y){
	memset(vis,0,sizeof vis);
	q.push({x,y,0});
	vis[x][y]=1;
	while(!q.empty()) {
		node now=q.front();
		q.pop();
		if(now.x==1&&now.y==1){
			cout<<now.ans<<endl;
			break;
		}
		for(int i=0; i<12; i++) {
			int xx=now.x+d[i][0];
			int yy=now.y+d[i][1];
			if(xx>=1&&xx<=x+2&&yy>=1&&yy<=y+2&&vis[xx][yy]==0) {
				vis[xx][yy]=1;
				q.push({xx,yy,now.ans+1});
			}
		}
	}
}
int main() {
	cin>>xa>>ya;
	bfs(xa,ya);
	cin>>xa>>ya;
	bfs(xa,ya);
	return 0;
}