#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double t1, t11;
  t1 = (double)d / v;
  t11 = t1;
  double sum = 0;
  while (t11 > g + r) {
    t11 = t11 - (g + r);
  }
  if (t11 >= g) {
    t11 -= g;
    t11 = r - t11;
  } else {
    t11 = 0;
  }
  l = l - d;
  double t2 = (double)l / v;
  t1 = t1 + t2;
  t1 = t1 + t11;
  printf("%.6f", t1);
}
