#include <bits/stdc++.h>
using namespace std;
const int N = 1e3 + 5, OO = 0x3f3f3f3f, MOD = 1000000007;
const double EPS = 0.000000001;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  long double t = d / v;
  while (t > g + r) {
    t -= g + r;
  }
  if (t < g) {
    cout << setprecision(9) << fixed << l / v;
  } else {
    cout << setprecision(9) << fixed << l / v + (g + r - t);
  }
}
