#include<bits/stdc++.h> 
using namespace std;
int a[21][21];
long long m,n,x,y;
int main(){
	cin>>m>>n>>x>>y;
	for(int i=0;i<=m;i++){
		for(int j=0;j<=n;j++){
			a[i][j]=1;
		}
	}
	a[x][y]=0;
	if(x-2>=0&&y+1<=n) {a[x-2][y+1]=0;}
	if(x-2>=0&&y-1>=0) {a[x-2][y-1]=0;}
	if(x-1>=0&&y+2<=n) {a[x-1][y+2]=0;}
	if(x-1>=0&&y-2>=0) {a[x-1][y-2]=0;}
	if(x+2<=n&&y+1<=n) {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<=n) {a[x+1][y+2]=0;}
	if(x+1<=n&&y-2>=0) {a[x+1][y-2]=0;}
	for(int i=0;i<=m;i++){
		for(int j=0;j<=n;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-1][j]+a[i][j-1];
			}
		} 
	}
	cout<<a[m][n];
	return 0;
}