N, M, P = map(int, input().split())
A = list(map(int, input().split()))
maxa = max(A)
from collections import defaultdict
dp = defaultdict(lambda: float('inf'))
check = defaultdict(lambda: False)
cnts = [1]*N
for i in range(N):
  while A[i]%P==0:
    cnts[i] += 1
    A[i] //= P
from heapq import *
lis = []
x = 1
dp[1] = 0
if max(A)==1 and maxa<=M:
  print(-1)
  exit() 
while x * maxa <= M:
  for i in range(N):
    dp[x*A[i]] = min(dp[x*A[i]], dp[x]+cnts[i])
    if not check[x*A[i]]:
      heappush(lis, x*A[i])
      check[x*A[i]] = True
  x = heappop(lis)
if x>M:
  print(dp[x])
else:
  print(dp[x]+1)