int main() {
        int n;
        cin >> n;
        double numArr[n];
        int index = 0;
        while (n != index) {
          int input;
      cin >> input;
      numArr[index] = input;
      index += 1;
    }

        sort(numArr, numArr + n);

        for (int i = 0; i < n-1; ++i) {
        double first = numArr[i] + numArr[i+1];
        numArr[i+1] = first / 2;
    }
        cout << numArr[n-1];

        return 0;
}