#include <bits/stdc++.h>
using namespace std;
int g, r, s, i;
double l, d, v;
int main() {
  cin >> l >> d >> v >> g >> r;
  s = g + r;
  for (i = 0; i <= 500; i++)
    if (s * i <= d / v && d / v <= s * (i + 1)) break;
  if (d / v < g)
    cout << fixed << setprecision(8) << l / v;
  else
    cout << fixed << setprecision(8) << (i + 1) * s + (l - d) / v;
  return 0;
}
