#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r, a, b, c = 0, n;
  int m, k1, k2;
  cin >> l >> d >> v >> g >> r;
  k1 = d / v;
  k2 = g + r;
  a = d / v;
  b = g + r;
  m = k1 % k2;
  n = floor(a / b);
  if (m < g) {
    cout << setprecision(8) << (l / v) << endl;
    return 0;
  } else if (m >= g) {
    cout << setprecision(8) << ((n * b + b) + ((l - d) / v)) << endl;
    return 0;
  }
  return 0;
}
