#include <bits/stdc++.h>
using namespace std;
int a[20][20]={0};
int f(int a[20][20],int b,int c) {
	if (a[b][c]==1) return 0;
	else {
		if (b==c && b==0) return 1;
		else if (b==0) return  f(a,b,c--);
		else if (c==0) return f(a,b--,c);
		else return  f(a,b,c--)+f(a,b--,c);
	}
}
int main () {
	int b,c,x,y,z=0;
	cin >> b >>c >>x >>y;
	a[x][y]=1;
	a[x-2][y-1]=1;
	a[x-1][y-2]=1;
	a[x-2][y+1]=1;
	a[x-1][y+2]=1;
	a[x+1][y+2]=1;
	a[x+2][y+1]=1;
	a[x+1][y-2]=1;
	a[x+2][y-1]=1;
	z =f(a,b,c);
	cout <<z;
	return 0;
}