10
-405 -230 252 -393 -390 -259 97 163 81 -129
 3
10000 -10000 10000
 1
-10000
 20
-16 -23 29 44 -40 -50 -41 34 -38 30 -12 28 -44 -49 15 50 -28 38 -2 0

702.333333333333712
 10000.000000000016371
 0.000000000000000
 113.875000000000043

#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, i, j, sum;
  cin >> n;
  int s[n + 1];
  for (i = 1; i <= n; i++) {
    cin >> s[i];
    if (s[i] < 0) s[i] = -s[i];
  }
  sort(s + 1, s + n + 1);
  cout << (s[1] + s[n]) / 2.00000000000;
  return 0;
}
