#include <iostream>

using namespace std;

int main(){
    int n;
    double x, a, b;
    cout << "Enter N: "; cin >> n;
    cout << "Enter X: "; cin >> x;
    cout << "Enter A: "; cin >> a;
    cout << "Enter B: "; cin >> b;
    double q=1;
    for (int i=1; i<=n; i++)
        q*=(i*a+x)/(i*b+x);
    cout << q;

}