#================================================
from functools import lru_cache
import sys,heapq
input=sys.stdin.readline
N,M,P=map(int,input().split())
A=list(set(map(int,input().split())))

D={}
for a in A:
    b=a
    m=1
    while a%P==0:
        a//=P
        m+=1
    D[b]=(m,a)

if not D:
    print(-1)
    exit(0)

T={1:0}
Q=[(0,1)]
heapq.heapify(Q)

while Q:
    d,x=heapq.heappop(Q)
    if x>M or d>T[x]:
        continue

    for b in D:
        m,a=D[b]
        if x*b>M and ((x*b not in T) or (T[x*b]>d+1)):
            T[x*b]=d+1
            Q.append((d+1,x*b))

        if a>1 and (x*a not in T) or T[x*a]>d+m:
            T[x*a]=d+m
            Q.append((d+m,x*a))


X=float("inf")
for x in T:
    if x>M:
        X=min(X,T[x])
print(X if X<float("inf") else -1)