#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:102400000,102400000")
using namespace std;
const int INF = 0x3f3f3f3f;
const long long INFF = 0x3f3f;
const double pi = acos(-1.0);
const double inf = 1e18;
const double eps = 1e-8;
const long long mod = 1e9 + 7;
const unsigned long long mx = 133333331;
inline void RI(int &x) {
  char c;
  while ((c = getchar()) < '0' || c > '9')
    ;
  x = c - '0';
  while ((c = getchar()) >= '0' && c <= '9') x = (x << 3) + (x << 1) + c - '0';
}
double a[105], b[105], c[300005];
int main() {
  int n;
  while (~scanf("%d", &n)) {
    double ans = 0;
    c[n] = 1;
    for (int i = 0; i < n; i++) {
      int x;
      scanf("%d", &x);
      a[i] = x / 100.0;
      b[i] = 1 - a[i];
      c[n] *= a[i];
    }
    ans += c[n] * n;
    for (int i = n + 1; i <= 300000; i++) {
      int j = 0;
      for (int k = 1; k < n; k++) {
        if ((1 - b[k] * (1 - a[k])) * (1 - b[j]) >
            (1 - b[j] * (1 - a[j])) * (1 - b[k]))
          j = k;
      }
      b[j] = b[j] * (1 - a[j]);
      c[i] = 1;
      for (int k = 0; k < n; k++) c[i] *= (1 - b[k]);
      ans += i * (c[i] - c[i - 1]);
    }
    printf("%.10lf\n", ans);
  }
  return 0;
}
