import sys
input = sys.stdin.readline
N, M, P = map(int, input().split())
a = list(map(int, input().split()))
a.sort()
x = 1
res = 1000
for i in range(N):
  y = a[i]
  c = 0
  while y % P == 0:
    y //= P
    c += 1
  if y == 1: continue
  t = 1
  for j in range(31):
    if t * a[-1] > M:
      res = min(res, (c + 1) * j + 1)
      break
    t *= y


for i in range(100):
  if x > M:
    print(min(res, i))
    break
  for j in range(N - 1, -1, -1):
    if (x * a[j]) % P or (x * a[j]) > M:
      x *= a[j]
      break
else:
  if res != 1000: print(res)
  else: print(-1)