#include<bits/stdc++.h>
using namespace std;
long long a[40][40];
int main()
{
	int n,m,x,y;
	cin>>n>>m>>x>>y;
	for(int i=0;i<=n;i++)
		for(int j=0;j<=m;i++)
			a[i][j]=1;
	a[x][y]=0;
	if(x+2<=n&&y-1>=0) a[x+2][y-1]=0;
	if(x+2<=n&&y+1>=0) a[x+2][y+1]=0;
	if(x+1<=n&&y+2>=0) a[x+1][y+2]=0;
	if(x-1<=n&&y+2>=0) a[x-1][y+2]=0;
	if(x-2<=n&&y+1>=0) a[x-2][y+1]=0;
	if(x-2<=n&&y-1>=0) a[x-2][y-1]=0;
	if(x-1<=n&&y-2>=0) a[x-1][y-2]=0;
	if(x+1<=n&&y-2>=0) a[x+1][y-2]=0;
	for(int i=0;i<n;i++)
		for(int j=0;j<m;j++)
		{
			if(i==0&&j==0)
				continue;
			if(a[i][j]==0)
				continue;
			if(i==0)
				a[i][j]=a[i][j-1];
			else if(j==0)
				a[i][j]=a[i-1][j];
			else
				a[i][j]=a[i-1][j]+a[i][j-1];
		}
	cout<<a[n][m];
	return 0;	
}