#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double ans = l * 1.0 / v;
  int t = (d / v) % (g + r);
  if (t >= 0 && t < g) {
    printf("%.7f", ans);
  } else {
    double tt = g * 1.0 + r * 1.0 - (d * 1.0 / v - (d / v) / (g + r) * (g + r));
    printf("%.7f", ans + tt);
  }
  return 0;
}
