#! /usr/bin/env python3

def main():
    C, D = map(int, input().split())
    A = min(C/(3/4), D/(1/4))
    max = A
    b = 0
    ab = A+b*2
    x = A
    for i in range(16):
        x /= 10
        c = 0
        while ab >= max:
            c += 1
            max = ab
            A -= x
            c, d = C-A*(3/4), D-A*(1/4)
            b = min(c/(2/7), d/(5/7))
            ab = A+b*2
        if c > 1:
            A += x*2
            c, d = C-A*(3/4), D-A*(1/4)
            b = min(c/(2/7), d/(5/7))
            ab = A+b*2
            max = ab
    print(max*1000)
if __name__ == '__main__':
    main()