#include <stdio.h>
#include<iostream>
#include <string.h>

using namespace std;

int cnt,xn,yn,m,n;
bool judge(int xn,int yn){
	if((xn+1==m&&yn+2==n)||
	(xn+1==m&&yn-2==n)||
	(xn-1==m&&yn+2==n)||
	(xn-1==m&&yn-2==n)||
	(xn-2==m&&yn+1==n)||
	(xn-2==m&&yn-1==n)||
	(xn+2==m&&yn+1==n)||
	(xn+2==m&&yn-1==n)
	)return 0;
	else return 1;
}
void dfs(int x,int y){
	if(x==xn&&y==yn){
		cnt++;
	return;
	}
	if(judge(x+1,y))dfs(x+1,y);
	if(judge(x,y+1))dfs(x,y+1);
}
int main()
{
    cin>>xn>>yn>>m>>n;
    dfs(0,0);
    cout<<cnt;
}