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

B = []
for a in A:
    cost = 1
    while a%P==0:
        a //= P
        cost += 1
    if a!=1:
        B.append((cost,a))

n = len(B)
dp = [1 for i in range(701)]
for i in range(n):
    cost,a = B[i]
    next = [dp[j] for j in range(701)]
    for j in range(701-cost):
        next[j+cost] = max(next[j+cost],min(M+1,dp[j]*a),min(M+1,next[j]*a))
    dp = next

K = max(A)
for i in range(701):
    if dp[i]*K >= M+1:
        print(i+1)
        break
else:
    print(-1)