#include <bits/stdc++.h>
using namespace std;
int main() {
  int l, d, v, g, r, dis;
  double t;
  while (scanf("%d%d%d%d%d", &l, &d, &v, &g, &r) == 5) {
    dis = l - d;
    t = d * 1.0 / v;
    if (t < (int)((t / (g + r))) * (g + r) + g &&
        t >= (int)(t / (g + r)) * (g + r))
      t = t + dis * 1.0 / v;
    else {
      t = (int)((t / (g + r))) * (g + r) + g + r + dis * 1.0 / v;
    }
    printf("%.8f\n", t);
  }
  return 0;
}
