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

D={}
for a in A:
    m=1
    while a%P==0:
        a//=P
        m+=1

    if a>1:
        if a in D:
            D[a]=min(m,D[a])
        else:
            D[a]=m

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

inf=float("inf")

@lru_cache(maxsize=10**6)
def f(x):
    if x>M:
        return 0

    g=inf
    for a,m in D.items():
        g=min(g,f(x*a)+m)
    return g

print(f(1))