#include <bits/stdc++.h>
using namespace std;
int main() {
  float l, d, v, g, r, t = 0, x, y, z, z2;
  cin >> l >> d >> v >> g >> r;
  if (d == l)
    t = t + (l / v);
  else {
    t = t + (d / v);
    l = l - d;
    x = t;
    while (x > 0) {
      y = x;
      x = x - g;
      if (x > 0) {
        y = x;
        x = x - r;
        if (x > 0)
          y = x;
        else {
          t = t + r;
          t = t - y;
          break;
        }
      } else if (x == 0) {
        t = t + r;
        break;
      } else
        break;
    }
    t = t + (l / v);
  }
  cout << setprecision(8) << t;
}
