#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r;
  double x1, x2;
  double t1, t2, t3, t4, t;
  int n;
  while (cin >> l >> d >> v >> g >> r) {
    t = 0;
    t1 = d / v;
    t = t1;
    t2 = (int)t1 % (int)(g + r);
    n = t1 / (g + r);
    if (t2 >= g) {
      t4 = t1 - n * (g + r);
      t += g + r - t4;
    }
    t3 = (l - d) / v;
    t += t3;
    printf("%.8f\n", t);
  }
  return 0;
}
