import sys

sys.setrecursionlimit(10**6)
int1 = lambda x: int(x)-1
p2D = lambda x: print(*x, sep="\n")
def II(): return int(sys.stdin.buffer.readline())
def MI(): return map(int, sys.stdin.buffer.readline().split())
def MI1(): return map(int1, sys.stdin.buffer.readline().split())
def LI(): return list(map(int, sys.stdin.buffer.readline().split()))
def LI1(): return list(map(int1, sys.stdin.buffer.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def BI(): return sys.stdin.buffer.readline().rstrip()
def SI(): return sys.stdin.buffer.readline().rstrip().decode()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
dij = [[(-1, 0), (1, 0)], [(0, -1), (0, 1)]]
inf = 10**16
# md = 998244353
md = 10**9+7

from collections import defaultdict

n,m,p=MI()
aa=LI()

cc=defaultdict(int)
for a in aa:
    k=0
    while a%p==0:
        a//=p
        k+=1
    cc[k]=max(cc[k],a)
# print(cc)

amx=max(aa)
t=(m+amx)//amx

def chmax(i,val):
    if i>64:return
    if val>dp[i]:dp[i]=val

dp=[-1]*65
dp[0]=1
for i in range(64):
    pre=dp[i]
    if dp[i]>=t:
        print(i+1)
        exit()
    if pre==-1:continue
    for k,c in cc.items():
        chmax(i+k+1,pre*c)
    # print(dp)

print(-1)