import sys
from collections import defaultdict

input = sys.stdin.buffer.readline


def solve(M, P, A):
    target = M // max(A) + 1
    d = defaultdict(int)

    for a in A:
        c = 1
        while a:
            if a % P:
                break
            a //= P
            c += 1
        d[c] = max(d[c], a)
    d = dict(d)

    if target == 1:
        return 1 if max(A) != 1 else -1

    if set(d.values()) == {1}:
        return -1

    MAX = 10000
    dp = [1] * (MAX + max(d) + 1)
    for i in range(MAX):
        if dp[i] >= target:
            return i + 1
        for k, v in d.items():
            dp[i + k] = max(dp[i + k], dp[i] * v)


N, M, P = map(int, input().split())
A = tuple(map(int, input().split()))
print(solve(M, P, A))