#include<bits/stdc++.h>
using namespace std;
int ch[30][30]={0};
bool flag[30][30]={false};
int main(){
	int a,b;
	cin>>a>>b;
	int x,y;
	cin>>x>>y;
	flag[x][y]=true;
	flag[x-1][y-2]=true;
	flag[x-2][y-1]=true;
	flag[x+1][y+2]=true;
	flag[x+2][y+1]=true;
	flag[x-1][y+2]=true;
	flag[x-2][y+1]=true;
	flag[x+1][y-2]=true;
	flag[x+2][y-1]=true;
	ch[0][0]=1;
	for(int i=0;i<=a;i++){
		for(int j=0;j<=b;j++){
			if(flag[i][j]==true)continue;
			else if(i==0&&j==0)continue;
			else ch[i][j]=ch[i-1][j]+ch[i][j-1];
		}
	}
/*	for(int i=0;i<=a;i++){
		for(int j=0;j<=b;j++){
			cout<<ch[i][j]<<' ';
		}
		cout<<endl;
	}*/
	cout<<ch[a][b];
	return 0;
}
/*
1 1 1 1 1 1 1
1 2 0 1 0 1 2
1 0 0 1 1 0 2
1 1 1 0 1 1 3
1 0 1 1 2 0 3
1 1 0 1 0 0 3
1 2 2 3 3 3 6*/

样例&&下载的数据都对，就是零分？？？