# import sys
# input = sys.stdin.readline
def mp():return map(int,input().split())
def lmp():return list(map(int,input().split()))
import math
import bisect
from copy import deepcopy as dc
from itertools import accumulate
from collections import Counter, defaultdict, deque
def ceil(U,V):return (U+V-1)//V
def modf1(N,MOD):return (N-1)%MOD+1

n,m,p = mp()
a = lmp()
if m < max(a):
    print(1)
    exit()
ag = []
for i in range(n):
    if math.gcd(a[i], p) == 1 and a[i] != 1:
        ag.append((a[i],1))
    else:
        cnt = 0
        while True:
            if a[i] % p == 0:
                cnt += 1
                a[i] //= p
            else:
                break
        if a[i] != 1:
            ag.append((a[i],1+cnt))
if not ag:
    print(-1)
    exit()
d = defaultdict(lambda:0)
for i in range(len(ag)):
    d[ag[i][1]] = max(d[ag[i][1]], ag[i][0])
d = list(d.items())  # 操作回数　かける数
stack = [(1,0)]  #今の数　操作回数
ans = int(1e10)
#print(d)
while stack:
    now = stack.pop()
    if now[0] > m:
        ans = min(ans,now[1])
        #print(now)
    elif now[0] >= ceil(m+1,max(a)):
        ans = min(ans,now[1]+1)
    else:
        for i,j in d:
            stack.append((now[0]*j, now[1]+i))
print(ans)