import heapq

n, m, p = map(int, input().split())
a = list(map(int, input().split()))
costs = [1] * n

for i in range(len(a)):
    while a[i] % p == 0:
        a[i] //= p
        costs[i] += 1

if all([ai == 1 for ai in a]):
    print(-1)
    exit()

def dijkstra(a, costs, m):
    distances = { 1 : 0 }
    queue = [(0, 1)]
    heapq.heapify(queue)
    INF = 1000000000
    
    while len(queue) > 0:
        c, v = heapq.heappop(queue)
        if c > distances.get(v, INF):
            continue
        elif v >= m:
            return c

        for i in range(len(a)):
            nxt = v * a[i]
            cst = c + costs[i]
            if cst < distances.get(nxt, INF):
                distances[nxt] = cst
                heapq.heappush(queue, (cst, nxt))
    
    return INF

print(dijkstra(a, costs, m))