#!/usr/bin/env python3
import sys


def solve(N: int, v: "List[int]"):
    v.sort()

    while(len(v) != 0):
        if(len(v) == 1):
            x = v.pop(0)
            print(x)
            exit()
        if(abs(v[0]-v[1]) < abs(v[-1]-v[-2])):
            a = v.pop(0)
            b = v.pop(0)
        else:
            a = v.pop(-1)
            b = v.pop(-1)
        v.append((a+b)/2)
        v.sort()
    

    return


# Generated by 1.1.4 https://github.com/kyuridenamida/atcoder-tools  (tips: You use the default template now. You can remove this line by using your custom template)
def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word
    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    v = [ int(next(tokens)) for _ in range(N) ]  # type: "List[int]"
    solve(N, v)

if __name__ == '__main__':
    main()
