from math import ceil

N, M, P = map(int,input().split())
A = list(map(int, input().split()))

M += 1
m = max(A)
if m>M:
    print(1)
    exit()
d = {}
for i in range(N):
    cnt = 1
    while A[i]%P==0:
        cnt += 1
        A[i] //= P
    if A[i]==1:
        continue
    if cnt in d:
        d[cnt] = max(d[cnt],A[i])
    else:
        d[cnt] = A[i]

if len(d)==0:
    print(-1)
    exit()
n = ceil(M/m)

dp = [0]*901
dp[0] = 1
for i in range(901):
    for key in d.keys():
        if i+key<=60:
            dp[i+key] = max(dp[i+key],dp[i]*d[key])
for i in range(901):
    if dp[i]>=n:
        print(i+1)
        exit()