#include<iostream>
using namespace std;
long long f[50][50],g[50][50];
int main()
{
    int n,m,p,q,ans;
    cin>>n>>m>>p>>q;

    g[p-1][q-2] = 1;
    g[p+1][q-2] = 1;
    g[p-2][q-1] = 1;
    g[p+2][q-1] = 1;
    g[p-2][q+1] = 1;
    g[p+2][q+1] = 1;
    g[p-1][q+2] = 1;
    g[p+1][q+2] = 1;
    g[p][q] = 1;


    for(int  i = 0;i<=n;i++)
        for(int j = 0;j<=m;j++)
            {
                f[0][0] = 1;
                if(j>0&&g[0][j]==0)  f[0][j] = f[0][j-1];
                if(i>0&&g[i][0]==0)  f[i][0] = f[i-1][0];
                if(i>=0&&j>=0&&g[i][j]==1)  f[i][j] = 0;
                if(i>=0&&j>=0&&g[i][j]==0)  f[i][j] = f[i-1][j]+f[i][j-1];
            }
    ans = f[n][m];
    cout<<ans;
    return 0;
}