#include <bits/stdc++.h>
using namespace std;
double f[100];
int k[100];
double cpw[100];
int N;
double calc(int i) { return (1 - cpw[i] * f[i]) / (1 - cpw[i]); }
int main() {
  cin >> N;
  int c;
  int highInc = 0;
  double P = 1;
  for (int i = 0; i < N; i++) {
    cin >> c;
    cpw[i] = f[i] = 1.0 - (c / 100.0);
    k[i] = 1;
    if (calc(i) > calc(highInc)) highInc = i;
    P *= (1 - f[i]);
  }
  double expval = 0;
  double oldP;
  for (int i = 1; i <= 300000; i++) {
    oldP = P;
    P *= calc(highInc);
    k[highInc]++;
    cpw[highInc] *= f[highInc];
    expval += i * (P - oldP);
    for (int j = 0; j < N; j++)
      if (calc(j) > calc(highInc)) highInc = j;
  }
  cout << fixed << setprecision(20) << expval + N << '\n';
}
