n,a,b,x,y=map(int,input().split())
h=list(map(int,input().split()))
h.sort(reverse=True)
k=1
q=h
while 1:
    h=q
    for j in h:
        if j-1<0:
            j=0
        else:
            j-=1
    k+=1
    q=h
    for i in range(a):
        if max(h)-x<0:
            h[h.index(max(h))]=0
        else :
            h[h.index(max(h))]-=x
    if sum(h)-y*b<=0:
        print(k)
        exit()