#include<bits/stdc++.h>
using namespace std;
long long f[300][300];
int main(){
	long long n,m,mx,my;
	cin>>n>>m>>mx>>my;
	mx++;
	my++;
	f[0][1]=1;
	for(int i=1;i<=n+1;i++){
		for(int j=1;j<=m+1;j++){
			if(i==mx&&j==my||i==mx+2&&j==my+1||i==mx+1&&j==my+2||i==mx-1&&j==my+2||i==mx+2&&j==my-1||i==mx+2&&j==my-1||i==mx+1&&j==my-2||i==mx-1&&j==my-2||i==mx-2&&j==my-1){
				f[i][j]=0;
				continue;
			}
			f[i][j]=f[i-1][j]+f[i][j-1];
		}
	}
	cout<<f[n+1][m+1]<<endl;
}