#include<bits/stdc++.h>
using namespace std;
int a[30][30];
int main()
{
    int n,m;
    int x,y;
    cin>>n>>m>>x>>y;
    for(int i = 0;i<=n;i++)
    {
        for(int j = 0;j<=m;j++)
        {
            a[i][j] = 1;
        }
    }
    a[x][y] = 0;
    if(x+2<=n && y+1<=m)     a[x+2][y+1] = 0;
    if(x+1<=n && y+2<=m)     a[x+1][y+2] = 0;
    if(x-1>=0 && y+2<=m)     a[x-1][y+2] = 0;
    if(x-2>=0 && y+1<=m)     a[x-2][y+1] = 0;
    if(x-2>=0 && y-1>=0)     a[x-2][y-1] = 0;
    if(x-1>=0 && y-2>=0)     a[x-1][y-2] = 0;
    if(x+1<=n && y-2>=0)     a[x+1][y-2] = 0;
    if(x+2<=n && y-1>=0)     a[x+2][y-1] = 0;
    for(int i = 0;i<=n;i++)
    {
        for(int j = 0;j<=m;j++)
        {
            if(a[i][j]==0) continue;
            if(i==0 && j==0) continue;
            if(i == 0)
            {
                a[i][j] = a[i][j-1];
            }
            else if(j == 0)
            {
                a[i][j] = a[i-1][j];
            }
            else
            {
                a[i][j] = a[i][j-1] + a[i-1][j];
            }
        }
    } 
    // for(int i = 0;i<=n;i++)
    // {
    //     for(int j = 0;j<=m;j++)
    //     {
    //         cout<<a[i][j]<<" ";
    //     }
    //     cout<<endl;
    // }
    cout<<a[n][m];
}
/**************************************************************
	Problem: 1224
	User: wuyichen
	Language: C++
	Result: Accepted
	Time:8 ms
	Memory:2076 kb
****************************************************************/