from itertools import *
from bisect import *
from collections import *
from heapq import *
import sys

sys.setrecursionlimit(10 ** 6)

def II(): return int(sys.stdin.readline())
def MI(): return map(int, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def SI(): return sys.stdin.readline()[:-1]
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
int1 = lambda x: int(x) - 1
def MI1(): return map(int1, sys.stdin.readline().split())
def LI1(): return list(map(int1, sys.stdin.readline().split()))
p2D = lambda x: print(*x, sep="\n")
dij = [(1, 0), (0, 1), (-1, 0), (0, -1)]

def main():
    def price(a):
        ac=a*3/4    # Aに使われるC
        ad=a/4  # Aに使われるD
        bc=c-ac # Bに使われるC
        bd=d-ad # Bに使われるD
        b=min(bc*7/2,bd*7/5)    # bc,bdから作れるB
        return a*1000+b*2000

    loop=100000
    c,d=MI()
    # 製品Aをa(kg)作るとして三分探索
    l=0
    r=min(c*4/3,d*4)
    for _ in range(loop):
        ml=(l*2+r)/3
        mr=(l+r*2)/3
        if price(ml)<price(mr):l=ml
        else:r=mr
    print(price(l))

main()