#include<bits/stdc++.h>
using namespace std;
int m,n,a,b;
long long ma[10][10],map1[10][10];
void bj(int x,int y)
{
    map1[x][y]=1;
    map1[x-2][y+1]=1;
    map1[x-2][y-1]=1;
    map1[x+2][y+1]=1;
    map1[x+2][y-1]=1;
    map1[x-1][y+2]=1;
    map1[x-1][y-2]=1;
    map1[x+1][y-2]=1;
    map1[x+1][y+2]=1;
}
int main()
{
    cin>>n>>m>>a>>b;
    bj(a,b);
    ma[1][0]=1;
    for(int i=1;i<=n+1;i++)
    {
        for(int j=1;i<=m+1;j++)
        {
            ma[i][j]=ma[i-1][j]+ma[i][j-1];
            if(map1[i-1][j-1])
            {
                ma[i][j]=0;
            }
        }
    }
    cout<<ma[n+1][m+1];
	return 0;
}