#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  int now = 0;
  int t = 0;
  while (1) {
    if (t % 2 == 0) {
      if (now + g * v > d) {
        double ans;
        ans = (double)l / v;
        printf("%.6lf\n", ans);
        break;
      } else if (now + g * v == d) {
        double ans;
        ans = (double)l / v;
        printf("%.6lf\n", ans + r);
        break;
      } else
        now += g * v;
    } else {
      if (now + r * v <= d) {
        now += r * v;
      } else {
        double ans;
        ans = (double)l / v + r - (double)(d - now) / v;
        printf("%.6lf\n", ans);
        break;
      }
    }
    t++;
  }
}
