#include <bits/stdc++.h>
double myfunc(double giv, int g, int r) {
  int sum = 0, f = 0;
  while (sum <= giv) {
    if (f == 0)
      sum = sum + g;
    else
      sum = sum + r;
    f = 1 - f;
  }
  if (f == 0)
    return sum - giv;
  else
    return 0;
}
int main() {
  int l, d, v, g, r, d1;
  double t1, t2, t3;
  scanf("%d%d%d%d%d", &l, &d, &v, &g, &r);
  d1 = (l - d);
  t1 = (double)d / v;
  t2 = myfunc(t1, g, r);
  t3 = (double)d1 / v;
  printf("%0.8f", t1 + t2 + t3);
  return 0;
}
