H,W,La,Lb,Ka,Kb = map(int,input().split())
high = H+W+100
low = 0
while high-low>1:
    mid = (high+low)//2
    cmax = 0
    for i in range(min((H+La-1)//La,mid)+1):
        j = min((W+Lb-1)//Lb,mid-i)
        cmax = max(cmax,i*j*La*Lb+i*Ka+j*Kb)
    if cmax>=H*W:
        high = mid
    else:
        low = mid
print(high)