#include<iostream>
#include<cstdio>

using namespace std;
long long n,m,dp[100][100],horse1,horse2;
int main(){/*n行m列*/
	cin>>n>>m;
	cin>>horse1>>horse2;
	dp[horse1+1][horse2-2]=0;
	dp[horse1+1][horse2+2]=0;
	dp[horse1-1][horse2+2]=0;
	dp[horse1-1][horse2-2]=0;
	dp[horse1+2][horse2-1]=0;
	dp[horse1+2][horse2+1]=0;
	dp[horse1-2][horse2+1]=0;
	dp[horse1+2][horse2-1]=0;
	dp[horse1-2][horse2-1]=0;
	
	for(int i=1;i<=n;i++){
		dp[i][1]=1;
	}
	for(int i=1;i<=m;i++){
		dp[1][i]=1; 
	}
	for(int i=2;i<=n;i++){
		for(int j=2;j<=m;j++){
			dp[i][j]=dp[i][j-1]+dp[i-1][j];
		}
	}
	cout<<dp[n][m];
	return 0;
}