#include<stdio.h>
long  long B[21][21];
 
int main(void)
{
int i,j,n,m,a,b;
scanf("%d%d%d%d",&n,&m,&a,&b);
for(i=0;i<=n;i++)
     for(j=0;j<=m;j++)
         B[i][j]=1;
if(a-2>=0&&b-1>=0)
B[a-2][b-1]=0;   
if(a-2>=0&&b+1<=m) 
B[a-2][b+1]=0;
if(a-1>=0&&b-2>=0)
B[a-1][b-2]=0;
if(a-1>=0&&b+2<=m)
B[a-1][b+2]=0;
if(a+1<=m&&b-2>=0)
B[a+1][b-2]=0;
if(a+2<=n&&b-1>=0)
B[a+2][b-1]=0;
if(a+1<=n&&b+2<=m)
B[a+1][b+2]=0;
if(a+1<=n&&b+1<=m)
B[a+2][b+1]=0;
B[a][b]=0;
for(i=0;i<=n;i++)
{
    for(j=0;j<=m;j++)
    {
        if(B[i][j])
        {
            if(i==0&&j==0) continue;
            else  if(i==0)  B[i][j]=B[i][j-1];
            else if(j==0)   B[i][j]=B[i-1][j];
            else B[i][j]=B[i-1][j]+B[i][j-1]; 
        }
    }
}
printf("%lld",B[n][m]);                /*第一次是用int  后来发现有点小改成long long  之后一直错  上网查了一下下午终于在下午五点发现输出居然用%d！！！ 这道题略坑，我早上11点做到17:55..只是因为这样一个错误。百密一疏呀。*/ 
    return 0;
}
/**************************************************************
	Problem: 1224
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1148 kb
****************************************************************/