#include <iostream>
#include <stdio.h>
#include <cmath>

using namespace std;
typedef pair<long double, long double> P;

int n;
long double p, q;
P unit;

P mul(P a, P b)
{
	return make_pair(a.first + b.first*a.second*a.second/(1-a.first*b.first), b.first*b.second/(1-a.second*b.first));
}

P calc(int n)
{
	if(n == 0) return make_pair(0, 1);
	if(n % 2){
		P tmp = calc(n-1);
		return mul(unit, tmp);
	}
	else{
		P tmp = calc(n/2);
		return mul(tmp, tmp);
	}
}

int main(void)
{
	cin >> n >> p >> q;
	unit = make_pair(p, q);
	printf("%.11Lf\n", calc(n).first);
	return 0;
}