#include <bits/stdc++.h>
template <typename T>
inline void read(T &x) {
  x = 0;
  char c = getchar();
  bool flag = false;
  while (!isdigit(c)) {
    if (c == '-') flag = true;
    c = getchar();
  }
  while (isdigit(c)) x = x * 10 + (c ^ 48), c = getchar();
  if (flag) x = -x;
}
using namespace std;
int n;
double p[121], mi[121], nw = 1;
double ans[1001000];
inline double calc(int cur) {
  return nw / (1.0 - mi[cur]) * (1.0 - mi[cur] * (1.0 - p[cur]));
}
int main() {
  read(n);
  for (int i = 1; i <= n; ++i) {
    int x;
    read(x);
    p[i] = x / 100.0;
    mi[i] = 1.0 - p[i];
    nw = nw * (1.0 - mi[i]);
  }
  ans[n] = nw;
  const int up = 400000;
  for (int t = n + 1; t <= up; ++t) {
    int mxid = 1;
    for (int i = 2; i <= n; ++i)
      if (calc(i) > calc(mxid)) mxid = i;
    ans[t] = calc(mxid);
    mi[mxid] *= (1.0 - p[mxid]);
    nw = ans[t];
  }
  double res = 0;
  for (int i = 1; i <= up; ++i) res += (ans[i] - ans[i - 1]) * i;
  printf("%.8f\n", res);
  return 0;
}
