#include <bits/stdc++.h>
using namespace std;
const int inf = (int)1e9;
const double eps = (double)1e-8;
const int mod = (int)1000000007;
const int maxn = (int)1e5 + 5;
long double p[102], q[102], g[102], c[300005], ch, c1, ans;
int n, mx;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cout << fixed << setprecision(10);
  cin >> n;
  for (int i = (1); i <= (n); i++) {
    cin >> p[i];
    p[i] = p[i] / (long double)100;
    q[i] = (long double)1 - p[i];
  }
  c[n] = (long double)1;
  ch = (long double)1;
  for (int i = (1); i <= (n); i++) {
    c[n] *= p[i];
    g[i] = q[i];
    ch *= p[i];
  }
  ans = c[n] * (long double)n;
  for (int i = (n + 1); i <= (300000); i++) {
    c[i] = (long double)0;
    mx = 0;
    for (int j = (1); j <= (n); j++) {
      c1 = (ch / ((long double)1 - g[j])) * ((long double)1 - g[j] * q[j]);
      if (c1 > c[i]) {
        c[i] = c1;
        mx = j;
      }
    }
    ch = (ch / ((long double)1 - g[mx])) * ((long double)1 - g[mx] * q[mx]);
    g[mx] *= q[mx];
    ans += (long double)i * (c[i] - c[i - 1]);
  }
  cout << ans;
  return 0;
}
