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]*1000
DP[0]=1

for i in range(950):
    for j in range(49,-1,-1):
        DP[i+j+1]=max(DP[i+j+1],DP[i]*K[j])
        
for i in range(1000):
    if DP[i]>M:
        print(i)
        break
else:
    print(-1)