#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r;
  scanf("%d %d %d %d %d", &l, &d, &v, &g, &r);
  double ans = 0;
  int k = d / (v * (g + r));
  if (d < (k * (r + g) + g) * v)
    ans += (double)d / v;
  else
    ans += (k + 1) * (r + g);
  ans += (double)(l - d) / v;
  printf("%.10f\n", ans);
  return 0;
}
