//=================================
// Created on: 2018/08/03 22:54:01
//=================================
#include <bits/stdc++.h>
#define show(x) std::cerr << #x << " = " << x << std::endl
using ll = long long;
using ld = long double;
constexpr ll MOD = 1000000007LL;
template <typename T>
constexpr T INF = std::numeric_limits<T>::max() / 10;
std::mt19937 mt{std::random_device{}()};
int main()
{
    int N, A, B;
    std::cin >> N >> A >> B;
    const ld R = 0.5 * (0.5 / A - 0.5 / B), X = 0.5 * (0.5 / A + 0.5 / B), Y = (ld)(N - 1) * R, C = -R * R + X * X + Y * Y;
    std::cout << std::fixed << std::setprecision(15) << R / C << std::endl;
    return 0;
}