n,m,p = map(int,input().split())
a = list(map(int,input().split()))
ans = float("INF")
ma = max(a)
if ma > m:
    print(1)
    exit()
MAX = [0]*40
for i in a:
    now = i
    count = 1
    while now%p == 0:
        now //= p
        count += 1
    if now == 1:
        continue
    MAX[count] = max(MAX[count],now)
dp = [0]*2000
dp[0] = 1
for i in range(1600):
    if ma * dp[i] > m:
        print(i+1)
        exit()
    for j in range(40):
        dp[i+j] = max(dp[i+j],dp[i]*MAX[j])
print(-1)