#include <stdio.h>
int juli(int x,int y,int m,int n){
	if((x-m)*(x-m)+(y-n)*(y-n)==5||(x==m&&y==n)) return 0;
	else return 1;
}
long long a[10000][10000]={0};
int main(){
	int wantx,wanty,max,may,i,j,k,flag;
	scanf("%d%d%d%d",&wantx,&wanty,&max,&may);
	for(i=0;i<=wantx;i++){
		a[i][0]=1;}
	for(i=0;i<=wanty;i++){
		a[0][i]=1;}
	for(i=1;i<=wantx;i++){
		for(j=1;j<=wanty;j++){
			flag=juli(i,j,max,may);
			printf("flag=%d\n",flag);
				if(flag)a[i][j]=a[i-1][j]+a[i][j-1];
				else continue;
		}
	}
	printf("%lld",a[wantx][wanty]);
	return 0;
}