#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, cas, n, l, d, v, r, g;
  double t1, t2, t3;
  while (scanf("%d%d%d%d%d", &l, &d, &v, &g, &r) != EOF) {
    t1 = d * 1.0 / (v * 1.0);
    t2 = t1;
    t1 += (l - d) * 1.0 / (v * 1.0);
    while (t2 >= g + r) t2 -= g + r;
    if (t2 - g > -0.000000001) t1 += g + r - t2;
    printf("%.8f\n", t1);
  }
  return 0;
}
