#include <bits/stdc++.h>
using namespace std;
int N, P[111];
double p[111];
priority_queue<pair<double, pair<double, int> > > pq;
int main(int argc, char *argv[]) {
  scanf("%d", &N);
  double prob = 1;
  for (int i = 0; i < (N); i++) {
    scanf("%d", P + i);
    p[i] = P[i] / 100.0;
    double pcur = 1 - (1 - p[i]) * (1 - p[i]);
    pq.push(make_pair(pcur / p[i], make_pair(p[i], i)));
    prob *= p[i];
  }
  double ans = N * prob;
  for (int step = (N + 1); step <= (200000); step++) {
    double pcur = pq.top().second.first;
    int i = pq.top().second.second;
    pq.pop();
    double prob_before = prob;
    prob /= pcur;
    pcur = 1 - (1 - pcur) * (1 - p[i]);
    prob *= pcur;
    pq.push(
        make_pair((1 - (1 - pcur) * (1 - p[i])) / pcur, make_pair(pcur, i)));
    ans += (prob - prob_before) * step;
  }
  printf("%.15lf\n", ans);
  return 0;
}
