#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  double arr[105];
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%lf", &arr[i]);
  sort(arr, arr + n);
  reverse(arr, arr + n);
  double Max = 0;
  double prev = 0, a = 0, b = 1;
  for (int i = 0; i < n; i++) {
    a = (a * (1 - arr[i])) + arr[i] * b;
    b *= (1 - arr[i]);
    Max = max(Max, a);
  }
  printf("%.10lf\n", Max);
  return 0;
}
