#include <iostream>
using namespace std;
int n,m,j,k;
int a[25][25];
int main(){
	cin >> n >> m >> j >> k;
	a[j][k]=0;
	a[j-2][k+1]=-1;
	a[j-1][k+2]=-1;
	a[j+1][k+2]=-1;
	a[j+2][k+1]=-1;
	a[j+2][k-1]=-1;
	a[j+1][k-2]=-1;
	a[j-1][k-2]=-1;
	a[j-2][k-1]=-1;
	for(int i=0;i<n;i++){
			a[i][0]=1;
		}
		for(int l=0;l<m;l++){
			a[0][l]=1;
		}
	for(int i=1;i<n;i++){
		for(int l=1;l<m;l++){
			if(a[i][l]==-1){
				a[i][l]=0;
			}else{
				a[i][l]=a[i-1][l]+a[i][l-1];
			}
		}
	}
	cout << a[n-1][m-1];
	return 0;
}