#include <bits/stdc++.h>
using namespace std;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') {
    x = x * 10 + ch - '0';
    ch = getchar();
  }
  return x * f;
}
long double f[2][111], g[2];
long double p[111];
long double ans;
int n;
int main() {
  ios::sync_with_stdio(false);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> p[i];
    p[i] /= 100.0;
  }
  ans = 1;
  for (int i = 0; i < 333333; i++) {
    int u = (i & 1);
    int v = u ^ 1;
    long double bv = 0;
    int bj = 0;
    for (int j = 1; j <= n; j++) {
      long double delta = (1 - f[u][j]) * p[j] / f[u][j];
      if (delta > bv) {
        bv = delta;
        bj = j;
      }
    }
    for (int j = 1; j <= n; j++) {
      if (j == bj)
        f[v][j] = f[u][j] + (1 - f[u][j]) * p[j];
      else
        f[v][j] = f[u][j];
    }
    if (f[u][bj] < 1e-10) {
      g[v] = 1;
      for (int j = 1; j <= n; j++) g[v] = g[v] * f[v][j];
    } else {
      g[v] = g[u] * f[v][bj] / f[u][bj];
    }
    ans += (g[v] - g[u]) * i;
  }
  cout << fixed << setprecision(15) << ans << endl;
  return 0;
}
