#include <iostream>
#include <cmath>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n); i++)

int main(){
    double n; cin >> n;
    double g; cin >> g;
    double v; cin >> v;
    double res = 0;
    res = floor(n / 5) * g / v;
    printf("%.12f\n",res);
    return 0;
}