H,W,LA,LB,KA,KB=map(int,input().split())

ANS=10**9

for yoko in range((H+LA-1)//LA+1):
    teki=H*W
    
    yoko_damage=W*min(H,yoko*LA)
    no_damage=teki-yoko_damage

    if no_damage>=KA*yoko:
        no_damage-=KA*yoko
    else:
        no_damage=0
        yoko_damage-=KA*yoko-no_damage

    #print(yoko,yoko_damage,no_damage)

    if yoko_damage<=0 and no_damage<=0:
        ANS=min(ANS,yoko)
        continue

    NG=0
    OK=10**6+1

    while OK>NG+1:
        mid=(OK+NG)//2

        rest=max(0,yoko_damage-min(W,mid*LB)*min(H,yoko*LA))+no_damage

        if mid*KB>=rest:
            OK=mid
        else:
            NG=mid

    #print(yoko,OK)
    ANS=min(ANS,yoko+OK)

print(ANS)