#include<bits/stdc++.h>
using namespace std;
using LL=long long;
using ULL=unsigned long long;
#define rep(i,n) for(int i=0; i<(n); i++)

ULL N,M,P;
ULL maxA;
ULL D[70];
ULL dp[5000];

int main(){
	scanf("%llu%llu%llu",&N,&M,&P);
	rep(i,70) D[i]=1;
	maxA=1;
	rep(i,N){
		ULL a; scanf("%llu",&a);
		int d=1;
		ULL b=a; while(b%P==0){ b/=P; d++; }
		D[d]=max(D[d],b);
		maxA=max(maxA,a);
	}
	rep(i,5000) dp[i]=1;
	M=M/maxA;
	int ans=-1;
	rep(i,5000){
		if(dp[i]>M){ ans=i+1; break; }
		rep(j,70){
			if(D[j]==1) continue;
			if(j==0) continue;
			if(i+j>=5000) continue;
			dp[i+j]=max(dp[i+j],dp[i]*D[j]);
		}
	}
	printf("%d\n",ans);
	return 0;
}