#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r, tmu;
  double tm, tmod;
  scanf("%d%d%d%d%d", &l, &d, &v, &g, &r);
  tmu = (int)((long double)(d / v) / (g + r));
  tmod = (double)d / v - tmu * (g + r);
  if (tmod < g)
    tm = (double)l / v;
  else
    tm = (double)l / v + (r - tmod + g);
  printf("%.8f\n", tm);
  return 0;
}
