#include<stdio.h>
int a[2][9]={-1,1,2,2,1,-1,-2,-2,0,-2,-2,-1,1,2,2,1,-1,0},i,j,n,m,x,y;
long long s[21][21]={};
int main()
{
scanf("%ld%ld%ld%ld",&n,&m,&x,&y);
for( i=0;i<9;i++)x+a[0][i]>=0&&y+a[1][i]>=0?s[x+a[0][i]][y+a[1][i]]=1:0;
for( i=0;i<=n;i++)
for(j=0;j<=m;j++)
s[i][j]=s[i][j]?0:!i^!j?!i?s[i][j-1]:s[i-1][j]:!i&&!j?1:s[i-1][j]+s[i][j-1];
printf("%ld",s[n][m]);
	return 0;
}