#include <bits/stdc++.h>
using namespace std;
int l, d, v, g, r, nowT;
double T;
int main() {
  scanf("%d%d%d%d%d", &l, &d, &v, &g, &r);
  T = 1. * d / v;
  for (int i = 1; i <= 10000; i++) {
    nowT += g;
    if (d < nowT * v) break;
    nowT += r;
    if (d < nowT * v) {
      T = nowT;
      break;
    }
  }
  T += 1. * (l - d) / v;
  printf("%.10lf\n", T);
}
