#include <bits/stdc++.h>
using namespace std;
int main() {
  double l, d, v, g, r, t, c = 0.0;
  int m = 1, s = 0, w = 0;
  cin >> l >> d >> v >> g >> r;
  t = d / v;
  while (1) {
    if (m % 2 != 0) {
      c = c + g;
      s++;
    }
    if (m % 2 == 0) {
      c = c + r;
      w++;
    }
    if (c > t) break;
    m++;
  }
  if (w < s) {
    t = l / v;
    printf("%.10f", t);
  } else {
    c = c + (l - d) / v;
    printf("%.10f", c);
  }
  return (0);
}
