#include <bits/stdc++.h>
using namespace std;
const double eps = 1e-8;
double l, d, v, g, r;
int main() {
  while (~scanf("%lf%lf%lf%lf%lf", &l, &d, &v, &g, &r)) {
    double ans = 0.0;
    ans += 1.0 * d / v;
    int tmp = (ceil)(ans / (g + r));
    if (1.0 * (tmp - 1) * (g + r) + g - ans > eps)
      ans = 1.0 * l / v;
    else
      ans = 1.0 * tmp * (g + r) + 1.0 * (l - d) / v;
    printf("%.8lf\n", ans);
  }
  return 0;
}
