#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r, p;
  double s, s1;
  cin >> l >> d >> v >> g >> r;
  s = 1.0 * d / v;
  p = (int)(s / (g + r));
  s1 = s - p * (g + r);
  if (s1 >= 0 && s1 < g) {
    s = 1.0 * l / v;
  } else {
    s += g + r - s1 + 1.0 * (l - d) / v;
  }
  printf("%.9lf\n", s);
}
