#include <bits/stdc++.h>
using namespace std;
inline long long read() {
  char c = getchar();
  long long fla = 1, k = 0;
  while (c < '0' || c > '9') {
    if (c == '-') fla = -1;
    c = getchar();
  }
  while (c >= '0' && c <= '9') {
    k = (k << 3) + (k << 1) + (c & 15);
    c = getchar();
  }
  return fla * k;
}
int n;
double p, q[110], po[110], ans;
priority_queue<pair<double, int> > que;
double getp(int id) { return (1 - po[id] * q[id]) / (1 - po[id]); }
int main() {
  n = read();
  p = 1;
  ans = n;
  for (int i = 1, x; i <= n; i++) {
    x = read();
    q[i] = (100 - x) * 1.0 / 100;
    po[i] = q[i];
    que.push(make_pair(getp(i), i));
    p *= (1 - q[i]);
  }
  for (int i = n + 1; i <= 300010; i++) {
    ans += 1 - p;
    pair<double, int> tmp = que.top();
    que.pop();
    p *= tmp.first;
    po[tmp.second] *= q[tmp.second];
    que.push(make_pair(getp(tmp.second), tmp.second));
  }
  printf("%.15lf", ans);
  return 0;
}
