#include <bits/stdc++.h>
int l, d, v, g, r;
int main() {
  std::cin >> l >> d >> v >> g >> r;
  int tt = d;
  while (tt >= v * (g + r)) {
    tt -= v * (g + r);
  }
  if (tt >= v * g) {
    printf("%.10lf", (double)(l + (r + g) * v - tt) / v);
  } else {
    printf("%.10lf", (double)l / v);
  }
  return 0;
}
