#include<bits/stdc++.h>
using namespace std;
int n,m,x,y;
long long bb[25][25];
bool a[25][25];
int dx[8]={-2,-2,-1,1,2,2,1,-1};
int dy[8]={-1,1,2,2,1,-1,-2,-2};
int main()
{
	cin>>m>>n>>x>>y;
	a[x][y]=1;
	for(int i=0;i<8;i++)
	if(x+dx[i]>=0&&x+dx[i]<=n&&y+dx[i]>=0&&y+dx[i]<=m)
		a[x+dx[i]][y+dx[i]]=1;
	for(int i=0;i<=n;i++)
		for(int j=0;j<=m;j++)
		{
			if(a[i][j]==1)  continue;
			if(i==0&&j==0) bb[i][j]=1;
			if(i==0&&j>0)  bb[i][j]=bb[i][j-1];
			if(i>0&&j==0)  bb[i][j]=bb[i-1][j];
			if(i>0&&j>0)   bb[i][j]=bb[i-1][j]+bb[i][j-1];
			
		}
	cout<<bb[n][m];
	return 0; 
}