#include<bits/stdc++.h>
using namespace std;

int main(){
  int n, g, v;
  double ans;
  
  cin >> n >> g >> v;
  
  int maisuu = n / 5;
  
  if(maisuu == 0){
    ans = 0;
  }else{
    ans = (double)maisuu * g / v;
  }

  printf("%0.7f\n", ans);
}