from fractions import Fraction


def main():

    N = int(input())
    elements = list(map(int,input().split()))
    elements.sort()

    while(len(elements)!=1):
        left = elements.pop(0)
        right = elements.pop(0)
        newElement = (left+right)/2
        elements.append(newElement)
    print(elements[0])



if __name__== "__main__":
    main() 









