#include<bits/stdc++.h>
using namespace std;
int main(){
	long long a[31][31],n,m,x,y;
	bool f[31][31];
	memset(a,0,sizeof(a));
	cin>>n>>m>>x>>y;
	f[x][y]=f[x-2][y-1]=f[x+2][y-1]=f[x-2][y+1]=f[x+2][y+1]=f[x-1][y-2]=f[x+1][y-2]=f[x-1][y+2]=f[x+1][y+2]=1;
	a[0][0]=1;
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			if(i==0&&j==0)continue;
			if(f[i][j])a[i][j]=0;
			else a[i][j]=a[i-1][j]+a[i][j-1];
		}
	}cout<<a[n][m];
	return 0;
}