#include <bits/stdc++.h>
int main() {
  int i, j, N, x;
  double v[1001], t[1001];
  scanf("%d", &N);
  for (i = 1; i <= N; i++) scanf("%lf", &v[i]);
  for (i = 1; i < N; i++) {
    for (j = i + 1; j <= N; j++) {
      if (v[i] > v[j]) {
        x = v[j];
        v[j] = v[i];
        v[i] = x;
      }
    }
  }
  printf("%lf", v[1]);
  for (i = 1; i < N; i++) {
    t[i] = (v[i] + v[i + 1]) / 2;
    v[i + 1] = t[i];
  }
  printf("%lf\n", v[N]);
  return 0;
}
