#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') f = -1;
  for (; isdigit(ch); ch = getchar()) x = x * 10 + ch - '0';
  return x * f;
}
const int maxn = 105;
int n;
double p[maxn], f[maxn];
double gl;
double Now(int a) { return f[a] + ((double)1 - f[a]) * p[a]; }
int main() {
  n = read();
  double last = 1;
  for (register int i = 1; i <= n; ++i) {
    p[i] = read(), p[i] /= (double)100;
    f[i] = p[i];
    last *= p[i];
  }
  double ans = (double)n * last;
  for (register int i = n + 1; i <= 300000; i++) {
    int tmp = 1;
    for (register int j = 1; j <= n; j++) {
      if (Now(j) / f[j] > Now(tmp) / f[tmp]) tmp = j;
    }
    gl = last * Now(tmp) / f[tmp];
    f[tmp] = Now(tmp);
    ans += (gl - last) * i;
    last = gl;
  }
  printf("%.10lf\n", ans);
  return 0;
}
