#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r;
  cin >> l >> d >> v >> g >> r;
  double ans;
  if (v * g >= l) {
    printf("%.8lf", l / v);
  } else {
    double ans2;
    double t = d / v;
    for (;;) {
      if (t > (g + r))
        t = t - g - r;
      else
        break;
    }
    if (t < g) {
      printf("%.8lf\n", l / v);
    } else {
      ans2 = (l - d) / (v);
      printf("%.8lf\n", l / v + (g + r) - t);
    }
  }
}
