#include <bits/stdc++.h>
using namespace std;
const int N = 105;
double l, d, v, g, r;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.precision(6);
  cin >> l >> d >> v >> g >> r;
  double temp = fmod((d / v), (g + r));
  if (temp < g) {
    cout << fixed << (double)l / (double)v << endl;
  } else {
    cout << fixed << d / v + abs(temp - (g + r)) + (l - d) / v << endl;
  }
  return 0;
}
