#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double ti;
  double ans;
  double kt = d * 1.0 / v;
  double tp = fmod(kt, g + r);
  if (tp >= g) {
    for (int i = 1; i <= 1000; ++i) {
      if (v * (g + r) * i > d) {
        ans += (g + r) * i;
        break;
      }
    }
    ans += (l - d) * 1.0 / v;
  } else {
    ans = l * 1.0 / v;
  }
  printf("%.8f\n", ans);
  return 0;
}
