#include<bits/stdc++.h>
using namespace std;
int n,m,x,y,a[22][22],dir[9][2]={{0,0},{2,1},{1,2},{-1,2},{-2,1},{-2,-1},{-1,-2},{1,-2},{2,-1}};
signed main(){
	a[2][2]=1;
	cin>>n>>m>>x>>y;
	for(int i=2;i<=n+2;i++){
		for(int j=2;j<=n+2;j++){
			if(i==2&&j==2){
				continue;
			}
			a[i][j]=a[i-1][j]+a[i][j-1];
			for(int k=0;k<9;k++){
				if(i==x-dir[k][0]&&j==y-dir[k][1]){
					a[i][j]=0;
					break;
				}
			}
		}
	}
	cout<<a[n+2][m+2]<<endl;
	return 0;
}