#include <bits/stdc++.h>
using namespace std;
double l, d, v, g, r, t, t1;
int main() {
  cin >> l >> d >> v >> g >> r;
  t = d / v;
  while (t1 < t) {
    if (t - t1 < g) break;
    t1 += g + r;
  }
  t = max(t, t1);
  t += (l - d) / v;
  printf("%.8f", t);
  return 0;
}
