#include <bits/stdc++.h>
using namespace std;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long T = 1;
  while (T--) {
    float a, b, c, d, e;
    cin >> a >> b >> c >> d >> e;
    long long x = b / (d + e), y;
    if (b > (c * (d + e))) {
      x = x * (d + e);
      x = x / c;
      if (b / c < x + d)
        printf("%0.8f\n", (a) / c);
      else
        printf("%0.8f\n", x + d + e + (a - b) / c);
      continue;
    }
    if (b < (c * d))
      printf("%0.8f\n", (a / c));
    else
      printf("%0.8f\n", e + d + (a - b) / c);
  }
  return 0;
}
