def main(n,m,p,a):
  ma0=max(a)
  if ma0>m:return 1
  b=[1]*n
  for i in range(n):
    while a[i]%p==0:
      a[i]//=p
      b[i]+=1
  ma1=max(a)
  if ma1==1:
    print(-1)
    exit()
  ary=[0]*50
  for i in range(n):
    ary[b[i]]=max(ary[b[i]],a[i])
  ary=[[i,v] for i,v in enumerate(ary) if v!=0]
  from heapq import heappush,heappop
  todo=[[0,1]]
  inf=float('inf')
  seen=[0]*1000
  seen[0]=1
  # seen[i]:操作回数i回における最大
  while todo:
    i,v=heappop(todo)
    if v*ma0>m:return i+1
    for di,dv in ary:
      if i+di<1000 and seen[i+di]<v*dv:
        seen[i+di]=v*dv
        heappush(todo,[i+di,v*dv])
n,m,p=map(int,input().split())
a=list(map(int,input().split()))
print(main(n,m,p,a))