#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);
}
long long numOfLines(int m,int n,int h_m,int h_n)
{
    if(!check(m,n,h_m,h_n))
    {
        return 0;
    }
    else if(m == 0 && n == 0)
    {
        return 1;
    }
    else if(m == 0 && n != 0)
    {
        return numOfLines(m,n-1,h_m,h_n);
    }
    else if(m != 0 && n == 0)
    {
        return numOfLines(m-1,n,h_m,h_n);
    }
    else
    {
        return numOfLines(m,n-1,h_m,h_n) + numOfLines(m,n-1,h_m,h_n);
    }
}
int main(){
    int m,n,h_m,h_n;
    cin >> m >> n >> h_m >> h_n;
    cout << numOfLines(m,n,h_m,h_n);
    return 0;
}