#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v;
  double g, r;
  while (~scanf("%lf%lf%lf%lf%lf", &l, &d, &v, &g, &r)) {
    double t1 = d / v;
    int k = t1 / (g + r);
    double t3 = t1 - k * (g + r);
    if (t3 < g)
      printf("%.8lf\n", l / v);
    else {
      printf("%.8lf\n", l / v + g + r - t3);
    }
  }
}
