#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r, t1 = 0, t2 = 0;
  cin >> l >> d >> v >> g >> r;
  if (v > 0) t1 = d / v;
  if (t1 < g && t1 > 0)
    t1 = 0;
  else if (t1 > g && t1 > 0) {
    while (1) {
      t1 -= g;
      if (t1 < r) {
        t1 = r - t1;
        break;
      }
      t1 -= r;
      if (t1 < g) {
        break;
      }
    }
  } else
    t1 = r;
  if (t1 < 0) t1 = 0;
  if (v > 0) t2 = (l / v) + t1;
  cout << fixed << setprecision(8) << t2;
}
