#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
using namespace std;

const int N = 100010;
int n, k;
double p, f[2][N];
int main() {
    #ifdef Kelly
        freopen("in.txt", "r", stdin);
        freopen("out.txt", "w", stdout);
        freopen("err.txt", "w", stderr);
    #endif
    cin >> n >> k >> p;
    if(k >= 170)    {cout << fixed << setprecision(10) << n * p / (1 - p);   return 0;}
    int cur = 0;
    for(int i = 0; i <= k; ++i, cur ^= 1) {
        f[cur][n] = 0;
        for(int j = n - 1; j >= 0; --j) {
            double tmp = pow(double(1) / (1 - p), j + 1) + f[cur][j + 1];
            if(i)   tmp = min(tmp, p * f[cur ^ 1][j] + (1 - p) * f[cur][j + 1] + 1);
            f[cur][j] = tmp;
        }
    }
    cout << fixed << setprecision(10) << f[cur ^ 1][0];
    return 0;
}