#include<bits/stdc++.h>
using namespace std;
long long int a[25][25];
bool pd[25][25];
int main(){
	int n,m,x,y;
	cin>>n>>m>>x>>y;
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			pd[i][j]=true;
		}
	}
	int p[10]={0,1,1,2,2,-1,-1,-2,-2};
	int q[10]={0,2,-2,1,-1,2,-2,1,-1};
	for(int i=0;i<9;i++){
		if((x+p[i])>=0&&(x+p[i])<=n&&(y+q[i]>=0)&&(y+q[i])<=m){
			pd[x+p[i]][y+q[i]]=false;
		}
	}
	for(int i=0;i<=n;i++){
		for(int j=0;j<=m;j++){
			if(i==0&&j==0) a[i][j]=1;
			else if(i==0&&j!=0) a[i][j]=a[i][j-1];
			else if(i!=0&&j==0) a[i][j]=a[i-1][j];
			else a[i][j]=a[i-1][j]+a[i][j-1];
			
			if(pd[i][j]==false) a[i][j]=0;
		}
	}
	cout<<a[n][m];
}