#include<bits/stdc++.h>
using namespace std;
int n,m,x,y;
int a[24][24];
long long f[24][24];
int main(){
	cin>>n>>m>>x>>y;
	f[2][0]=1;f[0][2]=1;
	a[x+1][y+1]=1;
	a[x+2][y+3]=a[x+3][y+2]=a[x+2][y-1]=a[x+3][y]=a[x][y+3]=a[x][y-1]=a[x-1][y+2]=a[x-1][y]=1;
	f[x+2][y+3]=f[x+3][y+2]=f[x+2][y-1]=f[x+3][y]=f[x][y+3]=f[x][y-1]=f[x-1][y+2]=f[x-1][y]=0;
	for(int i=1;i<=n+1;i++){
		for(int j=1;j<=m+1;j++){
			if(!a[i][j]){
				f[i][j]=f[i-1][j]+f[i][j-1];
			}
		}
	}
	f[x+2][y+3]=f[x+3][y+2]=f[x+2][y-1]=f[x+3][y]=f[x][y+3]=f[x][y-1]=f[x-1][y+2]=f[x-1][y]=0;
	cout<<f[n+1][m+1];
	return 0;
}