#include<stdio.h>
int main()
{
	int a,b,x,y,i,j;
	unsigned long long c[20][20]={0,1};
	scanf("%d%d%d%d",&a,&b,&x,&y);
	a+=1;b+=1;x+=1;y+=1;
	int fx[]={-2, -1, 1, 2, 2, 1, -1, -2};
	int fy[]={1, 2, 2, 1, -1, -2, -2, -1};
	c[x][y]=1;
	for(i=0;i<8;i++)
	c[x+fx[i]][y+fy[i]]=1;
    for(i=1;i<=a;i++)
	for(j=1;j<=b;j++)
	{
		if(c[i][j]==1)
		{
			c[i][j]=0;
			continue;
		}
		c[i][j]=c[i-1][j]+c[i][j-1];
	}
	printf("%llu",c[a][b]);	
	return 0;	
 }