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