#include <bits/stdc++.h>
using namespace std;
int l, d, v, g, r, t[10000], cur, cnt;
int main() {
  cin >> l >> d >> v >> g >> r;
  t[0] = 1;
  for (int i = 1; i <= 10000; i++) {
    if (cur == 0) {
      t[i] = 1;
      cnt++;
      if (cnt == g) {
        cnt = 0;
        cur = 1 - cur;
      }
    } else {
      t[i] = 2;
      cnt++;
      if (cnt == r) {
        cnt = 0;
        cur = 1 - cur;
      }
    }
  }
  int timme = floor((double)d / (double)v) + 1;
  if (t[timme] == 1) {
    printf("%.7lf\n", (double)l / (double)v);
  } else {
    while (t[timme] == 2) timme++;
    timme--;
    printf("%.7lf\n", timme + (double)(l - d) / (double)v);
  }
  return 0;
}
