#define M 1000
ll n,m,p,x,c,a[M],b[M],d[M*2];{rd(n,m,p,a(n));rep(i,n){x>?=a[i];c=1;while(a[i]%p==0)a[i]/=p,c++;b[c]>?=a[i];}rep(i,M){d[i]>?=1;rep(j,M)if(d[i]<=m)d[i+j]>?=d[i]*b[j];}rep(i,1010)if(d[i]*x>m){wt(i+1);return 0;}wt(-1);}