#include <iostream>
#include <stdio.h>
using namespace std;
typedef long long INT;

int main()
{
    INT N, G, V;
    cin >> N;
    cin >> G;
    cin >> V;
    INT n1 = (N / 5) * G;
    INT n2 = n1 / V;
    INT n3 = n1 - (n2 * V);
    cout << n2 << '.' << n3 * 100000000000 / V << endl;
}