def readint():
    return int(input())

def readints():
    return list(map(int, input().split()))

def calc(xs):
    ys = sorted(xs)[1:-1]
    return sum(ys) / len(ys)

def main():
    xs = readints()
    print("%.2f" % calc(xs))

if __name__ == "__main__":
    main()