#include <bits/stdc++.h>
using namespace std;
double p[1001000];
double v[110];
double pfoi[110];
int main() {
  int n;
  scanf("%d", &n);
  multiset<pair<double, int> > S;
  for (int i = 0; i < n; i++) {
    scanf("%lf", v + i);
    v[i] /= 100;
    S.insert(pair<double, int>(1e18, i));
  }
  for (int i = 1; i < 1001000; i++) {
    pair<double, int> u = *--S.end();
    S.erase(S.find(u));
    int a = u.second;
    pfoi[a] = pfoi[a] + (1.0 - pfoi[a]) * v[a];
    S.insert(pair<double, int>(1.0 + (1.0 - pfoi[a]) * v[a] / pfoi[a], a));
    p[i] = 1;
    for (int j = 0; j < n; j++) p[i] *= pfoi[j];
  }
  double ans = 0;
  for (int i = 1; i < 1001000; i++) ans += (p[i] - p[i - 1]) * i;
  printf("%.10lf\n", ans);
}
