#include <bits/stdc++.h>
using namespace std;
const int N = 105;
int n, x;
double p[N];
double q[N];
int c[N];
int main() {
  scanf("%d", &n);
  for (int i = 0; i < n; ++i)
    scanf("%d", &x), q[i] = 1 - (p[i] = x / 100.), c[i] = 1;
  int Limit = 400000;
  double E = 0;
  long double last = 0;
  for (int i = n; i < Limit; ++i) {
    long double a = 1;
    for (int j = 0; j < n; ++j) a *= 1 - q[j];
    E += i * (a - last);
    last = a;
    int k = 0;
    for (int j = 0; j < n; ++j)
      if ((1 - q[j] + q[j] * p[j]) * (1 - q[k]) >
          (1 - q[j]) * (1 - q[k] + q[k] * p[k]))
        k = j;
    q[k] *= 1 - p[k];
  }
  printf("%.9lf\n", E);
  return 0;
}
