#include <bits/stdc++.h>
double P[110], Res;
int w[110];
int n;
bool chk[110];
int main() {
  int i, j, x;
  double Mx, t, S, r;
  scanf("%d", &n);
  for (i = 1; i <= n; i++) {
    scanf("%d", &w[i]);
  }
  for (i = 1; i <= 1000000; i++) {
    Mx = 0.0;
    for (j = 1; j <= n; j++) {
      if (!chk[j]) break;
      t = P[j] + (1.0 - P[j]) * w[j] / 100.0;
      if (Mx < t / P[j]) {
        Mx = t / P[j];
        x = j;
      }
    }
    if (j != n + 1) {
      P[j] = w[j] / 100.0;
      chk[j] = true;
      if (i == n) {
        S = 1.0;
        for (j = 1; j <= n; j++) S *= P[j];
        Res += 1 - S;
      } else
        Res += 1.0;
      continue;
    }
    P[x] = P[x] + (1.0 - P[x]) * w[x] / 100.0;
    S = 1.0;
    for (j = 1; j <= n; j++) S *= P[j];
    Res += 1 - S;
  }
  printf("%.11f\n", Res + 1.0);
}
