#include <bits/stdc++.h>
using namespace std;
const long long INF = 1 << 28;
const long long LINF = 1ll << 61;
double p[111], ans, a[111];
int n;
int main() {
  cin >> n;
  double tp = 1;
  for (int i = 1; i <= n; i++) {
    int x;
    cin >> x;
    p[i] = 1.0 / 100 * x;
    a[i] = 1 - p[i];
    tp *= (1 - a[i]);
  }
  double pre = tp, now = 0;
  ans += pre * n;
  for (int i = n; i <= 200000; i++) {
    now = 1;
    for (int j = 1; j <= n; j++) now *= (1 - a[j]);
    int it = 1;
    for (int j = 1; j <= n; j++)
      if (now / (1 - a[j]) * (1 - a[j] * (1 - p[j])) >
          now / (1 - a[it]) * (1 - a[it] * (1 - p[it])))
        it = j;
    now /= 1 - a[it];
    a[it] *= (1 - p[it]);
    now *= 1 - a[it];
    ans += (i + 1) * (now - pre);
    pre = now;
  }
  cout << fixed << setprecision(12) << ans << endl;
  return 0;
}
