#include <bits/stdc++.h>

//#define long long long int
#define double long double
#define DEBUG
using namespace std;

// @author: pashka

int main() {
    ios::sync_with_stdio(false);

    cout << setprecision(20);

    int n, k;
    cin >> n >> k;

    double p;
    cin >> p;

    if (1.0 * n * k > 2e7) {
        cout << n / (1 - p) << "\n";
        return 0;
    }

    vector<double> t(n + 1);
    for (int i = 1; i <= n; i++) {
        t[i] = (t[i - 1] + 1) / (1 - p);
    }

    if (k == 0) {
        cout << t[n] << "\n";
        return 0;
    }

    vector<double> d = t;

//    for (double x: d) cout << x << " ";
//    cout << "\n";
    for (int i = 0; i < k + 1; i++) {
        vector<double> dd(n + 1);
        for (int j = 1; j <= n; j++) {
            dd[j] = dd[j - 1] + (t[n - j] + 1) * p / (1 - p) + 1;
            if (i > 0) {
                dd[j] = min(
                        dd[j],
                        (1 - p) * dd[j - 1] + p * d[j] + 1
                );
            }
        }
        d = dd;
//        for (double x: d) cout << x << " ";
//        cout << "\n";
    }
    cout << d[n] << "\n";

    return 0;
}