#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

int main() {
    int n;
    cin >> n;

    double p, q;
    cin >> p >> q;

    double x[1002][2] = {};

    x[0][0] = 1;
    x[n + 1][1] = 0;
    for (int i = 1; i <= n; i++) {
        x[i][0] = 0.5;
    }

    for (int h = 0; h < 100000; h++) {
        for (int i = 1; i <= n; i++) {
            x[i][0] = q * x[i - 1][0] + p * x[i + 1][1];
            x[i][1] = p * x[i - 1][0] + q * x[i + 1][1];
        }
    }

    printf("%.8f\n", x[1][1]);

    return 0;
}