n, m, p = map(int, input().split())
a = list(map(int, input().split()))
d = list()
cnt = list()
flag = True
for c in a:
    tmp = 0
    while c % p == 0:
        c //= p
        tmp += 1
    if c > 1:
        flag = False
    d.append(c)
    cnt.append(tmp)
if flag:
    print(-1)
    exit()

dp = [1] * (100000)


for i in range(100000):
    now = dp[i]
    if now > m:
        print(i)
        exit()
    for j in range(n):
        c = a[j]
        if now * c > m:
            print(i + 1)
            exit()
        dp[i + cnt[j] + 1] = max(dp[i + cnt[j] + 1], now * d[j])