import sys
input = sys.stdin.readline

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

B=[0]*N
C=[0]*N

for i in range(N):
    a=A[i]
    while a%P==0:
        B[i]+=1
        a//=P
    C[i]=a

K=[0]*50

for i in range(N):
    K[B[i]]=max(K[B[i]],C[i])


DP=[0]*100000
DP[0]=1

for i in range(95000):
    for j in range(49,-1,-1):
        DP[i+j+1]=min(10**9+1,max(DP[i+j+1],DP[i]*K[j]))

MAX=max(A)
for i in range(100000):
    if DP[i]>M/MAX:
        print(i+1)
        break
else:
    print(-1)