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

K, K2 = 35, 70
D = [1] * K
for i in range(N):
    cnt = 0
    while A[i] % P == 0:
        cnt += 1
        A[i] //= P
    D[cnt] = max(D[cnt], A[i])

inf = 10 ** 18
dp = [-inf] * K2
dp[0] = 1
for i in range(K2):
    if dp[i] * ma > M:
        print(i + 1)
        exit()
        
    for j in range(K):
        if i + j + 1 >= K2:
            break
        dp[i + j + 1] = max(dp[i + j + 1], dp[i] * D[j])
        
print(-1)