#include <bits/stdc++.h>
using namespace std;
inline void xxx() {}
inline int rd(int l, int r) { return rand() % (r - l + 1) + l; }
const int mxn = 103;
int n;
double g[mxn], a[mxn];
double ans;
priority_queue<pair<double, int> > q;
int main() {
  double gg = 1;
  scanf("%d", &n);
  for (int i = 1, x; i <= n; ++i)
    scanf("%d", &x), g[i] = x / 100.0, gg *= g[i], a[i] = g[i];
  ans = n * gg;
  for (int i = 1; i <= n; ++i)
    q.push(pair<double, int>((1 - a[i]) / a[i] * g[i], i));
  for (int T = 1; T <= 3e5; ++T) {
    double x = q.top().first;
    int i = q.top().second;
    q.pop();
    ans += gg * x * (T + n);
    gg /= a[i];
    a[i] += (1 - a[i]) * g[i];
    gg *= a[i];
    q.push(pair<double, int>((1 - a[i]) / a[i] * g[i], i));
  }
  printf("%.7f\n", ans);
  return 0;
}
