#include <bits/stdc++.h>
using namespace std;
static const double EPS = 1e-9;
double getTime(double t, double g, double r) {
  double n = floor(t / (g + r) + EPS);
  if (t < n * (g + r) + g - EPS) return t;
  return (n + 1.0) * (g + r);
}
int main(void) {
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double dt = d / v;
  double ans = (l - d) / v + getTime(dt, g, r);
  printf("%.10f\n", ans);
  return 0;
}
