from math import floor


def main():
    N = int(input())
    v = list(map(int, input().split(" ")))
    while len(v) > 1:
        v.sort()
        w = []
        if len(v) % 2 == 1:
            w.append(v[-1])
            N -= 1
        for i in range(floor(N / 2)):
            w.append((v[i * 2] + v[i * 2 + 1]) / 2)
        v = w
    print(v[0])


if __name__ == '__main__':
    main()