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