#include<iostream>
#include<algorithm>
using namespace std;

bool check(int x, int y,int m, int n){
    return ((x-m)*(x-m)+
    (y-n)*(y-n))!=5 && !(x == m || y == n);
}

int main(){
    int m,n,h_m,h_n;
    cin >> m >> n >> h_m >> h_n;
    int a[m+1][n+1];
    for (int i = 0;i < m; i++)
    {
        for (int j = 0; j < n; j++)
        {
            if(!check(m,n,h_m,h_n))
            {
                a[i][j] = 0;
            }
            else if(i == 0 && j == 0)
            {
                a[i][j] = 1;
            }
            else if(i == 0 && j != 0)
            {
                a[i][j] = a[i][j-1];
            }
            else if(i != 0 && j == 0)
            {
                a[i][j] = a[i][j-1];
            }
            else
            {
                a[i][j] = a[i][j-1] + a[i-1][j];
            }
        }
    }
    cout << a[m-1][n-1];
    
    return 0;
}