#include <bits/stdc++.h>
using namespace std;
int n;
double p[101], f[101], ans = 0, last = 1;
double Calc(int x) { return 1 - (1 - f[x]) * (1 - p[x]); }
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) {
    int x;
    cin >> x;
    p[i] = f[i] = x / 100.0;
    last *= p[i];
  }
  ans += last * n;
  for (int i = n + 1; i <= 300000; i++) {
    int x = 1;
    for (int j = 1; j <= n; j++) {
      if (Calc(j) / f[j] > Calc(x) / f[x]) x = j;
    }
    double now = last * Calc(x) / f[x];
    f[x] = Calc(x);
    ans += (now - last) * i;
    last = now;
  }
  printf("%.8f\n", ans);
}
