#include <bits/stdc++.h>
using namespace std;
double l, d, v, g, r;
int main() {
  scanf("%lf %lf %lf %lf %lf", &l, &d, &v, &g, &r);
  double t = 0;
  t += d / v;
  double p = t - floor(t / (g + r)) * (g + r);
  if (p < g)
    ;
  else
    t = ceil(t / (g + r)) * (g + r);
  t += (l - d) / v;
  printf("%.8f\n", t);
}
