#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
#define yn {puts("Yes");}else{puts("No");}
#define MAX_N 200005

int main() {
    ll n, g, v;
    cin >> n >> g >> v;

    ll x = (n / 5) * g;

    cout << x / v;
    x -= x / v * v;
    cout << '.';
    x *= 1000000000;
    cout << setfill('0') << right << setw(9) << x / v;
    x -= x / v * v;
    x *= 1000000000;
    cout << setfill('0') << right << setw(9) << x / v << endl;
    
    return 0;
}