#include<iostream>
using namespace std;
int n,m,hx,hy,a[8],b[8];
int p(int x,int y)
{
    if(x==n&&y==m)
    {
        return 1;
    }
    if(x>n||y>m)
    {
        return 0;
    }
    for(int i=1;i<=7;i++)
    {
        if(x==a[i]&&y==b[i])
        {
            return 0;
        }
    }
    return p(x-1,y)+p(x,y-1);
}
int main()
{
    cin>>n>>m>>hx>>hy;
    a[0]=hx+1;
    a[1]=hx+2;
    a[2]=hx+2;
    a[3]=hx+1;
    a[4]=hx-1;
    a[5]=hx-2;
    a[6]=hx-2;
    a[7]=hx-1;
    b[0]=hy+2;
    b[1]=hy+1;
    b[2]=hy-1;
    b[3]=hy-2;
    b[4]=hy-2;
    b[5]=hy-1;
    b[6]=hy+1;
    b[7]=hy+2;
    cout<<p(0,0);
    return 0;
}