#include <bits/stdc++.h>
const int N = 150;
int n;
double p[N];
void init() {
  std::cin >> n;
  for (int i = 1; i <= n; i++) {
    scanf("%lf", &p[i]);
    p[i] /= 100.0;
  }
}
void work() {
  static double f[N];
  for (int i = 1; i <= n; i++) {
    f[i] = 1.0;
  }
  double answer = 1.0;
  double pr = 1.0;
  for (int t = 2; t <= 500000; t++) {
    int best = -1;
    for (int i = 1; i <= n; i++) {
      if (best == -1 || (1.0 - f[i] * (1.0 - p[i])) * (1.0 - f[best]) >
                            (1.0 - f[best] * (1.0 - p[best])) * (1.0 - f[i])) {
        best = i;
      }
    }
    f[best] *= 1.0 - p[best];
    pr = 1.0;
    for (int i = 1; i <= n; i++) {
      pr *= 1.0 - f[i];
    }
    answer += 1.0 - pr;
  }
  printf("%.10f\n", answer);
}
int main() {
  init();
  work();
  return 0;
}
