#include <bits/stdc++.h>
using namespace std;
int n,m,s=0,dx[2]={0,1},dy[2]={1,0},mx,my,sss=0;
bool used[25][25];
void dfs(int x,int y){
	if(x+1==n&&y+1==m){
	s++;
	return;
	}
	for(int i=0;i<=1;i++){
		int nx=x+dx[i];
		int ny=y+dy[i];
		if(nx>=0&&nx<n&&ny>=0&&ny<m&&used[nx][ny]==0){
			used[nx][ny]=1;
			dfs(nx,ny);
			used[nx][ny]=0;
		}
	}
	return;
}
int main(){
	cin>>n>>m;
	cin>>mx>>my;
	used[mx][my]=used[mx-1][my+2]=used[mx-1][my-2]=used[mx-2][my+1]=used[mx-2][my-1]=used[mx+1][my+2]=used[mx+1][my-2]=used[mx+2][my+1]=used[mx+2][my-1]=1;
	dfs(0,0);
	cout<<s;
	return 0;
}

2紫2红1黑，求神犇帮忙