#include<iostream>
#include<algorithm>
#include<cstdio>
#define int long long
using namespace std;
int n,m,x,y,ans;
bool a[21][21];
signed main()
{
	scanf("%d%d%d%d",&n,&m,&x,&y);
	a[x][y]=2e9;
	if(x-2>=0&&y-1>=0) a[x-2][y-1]=2e9;
	if(x-2>=0&&y+1>=0) a[x-2][y+1]=2e9;
	if(x-1>=0&&y-2>=0) a[x-1][y-2]=2e9;
	if(x-1>=0&&y+2>=0) a[x-1][y+2]=2e9;
	if(x+1>=0&&y-2>=0) a[x+1][y-2]=2e9;
	if(x+1>=0&&y+2>=0) a[x+1][y+2]=2e9;
	if(x+2>=0&&y-1>=0) a[x+2][y-1]=2e9;
	if(x+2>=0&&y+1>=0) a[x+2][y+1]=2e9;
	for(int i=0;i<=n;i++) a[i][0]=1;
	for(int i=0;i<=m;i++) a[0][i]=1;
	for(int i=1;i<=n;i++)
	{
		for(int j=1;j<=m;j++)
		{
			if(a[i][j]==2e9) a[i][j]=0;
			else a[i][j]=a[i-1][j]+a[i][j-1];
		}
	}
	printf("%d",a[n][m]);
	return 0;
}