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