import sys

def resolve(in_):
    N = next(in_).strip()
    A = list(map(int, next(in_).split()))
    A.sort()

    if len(A) % 2:
        ans = A[len(A) // 2]
    else:
        x = len(A) // 2
        ans = (A[x - 1] + A[x]) / 2
    return '{:.1f}'.format(ans)


def main():
    ans = resolve(sys.stdin)
    print(ans)


if __name__ == '__main__':
    main()