#include <iostream>
using namespace std;
int main(){
	long long a[25][25]={1},f[25][25]={0},n,m,bx,by;
	int fx[] = {0, -2, -1, 1, 2, 2, 1, -1, -2},fy[] = {0, 1, 2, 2, 1, -1, -2, -2, -1};
	cin >> bx >> by >> n >> m;
	a[0][0]=1;
	for(int i=0;i<9;i++)f[fx[i]+n][fy[i]+m]=1;
	for(int i=0;i<=bx;i++){
		for(int j=0;j<=by;j++){
			if(f[i][j])continue;
			else if(i!=0&&j!=0)a[i][j]=a[i-1][j]+a[i][j-1];
			else a[i][j]=1;
		}
	}
	cout << a[bx][by];
	return 0;
}