#include <stdio.h>
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf 1000000000000


int main(){

	long long N,M,P;
	cin>>N>>M>>P;
	
	long long ans = 0;
	vector<long long> A(N),B(N,0);
	long long maxi = 0LL;
	vector<long long> mul(31,0LL);
	rep(i,N){
		cin>>A[i];
		//maxi = max(maxi,A[i]);
		while(A[i]%P==0){
			A[i]/=P;
			B[i]++;
		}
		mul[B[i]] = max(mul[B[i]],A[i]);
		maxi = max(maxi,A[i]);
	}

	
	vector<long long> dp(1000,0LL);
	dp[0] = 1;
	
	rep(i,31){
		rep(j,1000){
			if(j+i+1<1000){
				dp[j+i+1] = max(dp[j+i+1],dp[j] * mul[i]);
				dp[j+i+1] = min(dp[j+i+1],10000000005LL);
			}
		}
	}
	
	
	
	rep(i,dp.size()){
		if(dp[i]*maxi>M){
			cout<<i+1<<endl;
			return 0;
		}
	}
	
	cout<<-1<<endl;
	
    return 0;
}