#include<bits/stdc++.h>
using namespace std;

int a[30][30],n,m,x,y;

int main(){
	scanf("%d%d%d%d",&n,&m,&x,&y);
	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 - 1][j] + a[i][j - 1];
				}
			}
		}
	}
	printf("%d",a[n][m]);
	return 0;
}