#include<bits/stdc++.h>
using namespace std;
long long vis[100][100],p[100][100],m,n,c1,c2;
int main()
{
	cin>>m>>n>>c1>>c2;
	c1++,c2++,m++,n++;
	vis[c1][c2]=1;
	vis[c1-2][c2-1]=1;
	vis[c1+2][c2-1]=1;
	vis[c1-2][c2+1]=1;
	vis[c1+2][c2+1]=1;
	vis[c1-1][c2-2]=1;
	vis[c1-1][c2+2]=1;
	vis[c1+1][c2-2]=1;
	vis[c1+1][c2+2]=1;
	for (int i=1;i<=m;i++)
	{
		p[i][1]=1;
	}
	for (int i=1;i<=n;i++)
	{
		p[1][i]=1;
	}
	for (int i=1;i<=m;i++)
	{
		for (int j=1;j<=n;j++) 
		{
			if(vis[i][j]==0&&(i!=1||j!=1))
			{
				p[i][j]=p[i-1][j]+p[i][j-1];
			    vis[i][j]=1;
			}
		}
	}
	cout<<p[m][n]<<" ";

	return 0;
}