#include <bits/stdc++.h>
using namespace std;
const int nMax = 1e5 + 10;
int main() {
  double l, d, v, g, r;
  scanf("%lf%lf%lf%lf%lf", &l, &d, &v, &g, &r);
  double t1 = d / v;
  if (t1 < g) {
    printf("%.8f\n", l / v);
  } else {
    int num = t1 / (g + r);
    double t2 = t1 - (g + r) * num;
    if (t2 < g)
      printf("%.8lf\n", l / v);
    else
      printf("%.8lf\n", l / v + (g + r) - t2);
  }
}
