"""

dp[i] = i回の操作で行ける最大値

"""


from sys import stdin
import sys

N,M,P = map(int,stdin.readline().split())
A = list(map(int,stdin.readline().split()))
B = []
cnt = [0] * N

for i in range(N):
    na = A[i]
    while na % P == 0:
        na //= P
        cnt[i] += 1
    B.append(na)

if max(B) == 1 and max(A) <= M:
    print (-1)
    sys.exit()

dp = [1] * 1001
for i in range(1000):
    
    nmax = dp[i]
    if nmax > M:
        print (i)
        break

    for j in range(N):
        if nmax * A[j] > M:
            print (i+1)
            sys.exit()
        else:
            dp[i+1+cnt[j]] = max(dp[i+1+cnt[j]] , dp[i]*B[j])