#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline bool upmin(T &x, T y) {
  return y < x ? x = y, 1 : 0;
}
template <typename T>
inline bool upmax(T &x, T y) {
  return x < y ? x = y, 1 : 0;
}
const long double eps = 1e-11;
const long double pi = acos(-1);
const int oo = 1 << 30;
const long long loo = 1ll << 62;
const int mods = 998244353;
const int MAXN = 600005;
const int INF = 0x3f3f3f3f;
inline int read() {
  int f = 1, x = 0;
  char c = getchar();
  while (c < '0' || c > '9') {
    if (c == '-') f = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    x = (x << 3) + (x << 1) + (c ^ 48);
    c = getchar();
  }
  return x * f;
}
long double p[MAXN], f[MAXN];
long double get(int x) { return f[x] + p[x] * (1 - f[x]); }
signed main() {
  int n = read();
  long double lst = 1;
  for (int i = 1; i <= n; i++) p[i] = f[i] = read() * 0.01, lst *= p[i];
  long double ans = n * lst;
  for (int Case = n + 1; Case <= 300000; Case++) {
    int mn = 1;
    for (int i = 1; i <= n; i++)
      if (get(i) / f[i] > get(mn) / f[mn]) mn = i;
    long double nw = lst * get(mn) / f[mn];
    f[mn] = get(mn), ans += (nw - lst) * Case, lst = nw;
  }
  printf("%.11lf\n", (double)ans);
  return 0;
}
