#include <bits/stdc++.h>
using namespace std;
const int MAXN = 105;
double f[MAXN], p[MAXN], ans, lst = 1, g;
inline int read() {
  int x = 0;
  char ch = getchar();
  while (!isdigit(ch)) ch = getchar();
  while (isdigit(ch)) {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x;
}
inline double calc(int x) { return (f[x] + (1 - f[x]) * p[x]) / f[x]; }
inline double calc2(int x) { return f[x] + (1 - f[x]) * p[x]; }
int main() {
  int n = read();
  for (int i = 1; i <= n; i++) p[i] = f[i] = read() / 100.0;
  for (int i = 1; i <= n; i++) lst *= p[i];
  ans = lst * n;
  for (int i = n + 1; i <= 300000; i++) {
    int tmp = 1;
    for (int j = 1; j <= n; j++)
      if (calc(j) > calc(tmp)) tmp = j;
    g = lst * calc(tmp), f[tmp] = calc2(tmp), ans += (g - lst) * i, lst = g;
  }
  printf("%.8lf\n", ans);
  return 0;
}
