#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double out = 0, time, h;
  out += 1.0 * d / v;
  if (g <= out) {
    time = out;
    while (g + r <= time) time = time - g - r;
  }
  if (g <= time) {
    h = time - g;
    h = r - h;
    out += h;
  }
  out += 1.0 * (l - d) / v;
  cout << setprecision(8) << out;
  return 0;
}
