#include<bits/stdc++.h>
// #include<atcoder/all>
using namespace std;
// using namespace atcoder;
using lint = long long;
#define endl '\n'
lint const mod = 1e9+7;
//long const mod = 998244353;
map<lint,lint>dp;
lint maxx;

    lint n,m,p;
    lint a[200000];
    map<lint,lint>cost;
lint search(lint x){
    if(x*maxx > m)return 1;
    if(dp[x] != 0)return dp[x];
    lint tmp = 1<<30;
    for(auto pp: cost){
        tmp = min(tmp, search(x*pp.second) + pp.first);
    }
    return dp[x] = tmp;
    
}

int main(){
    cin >> n >> m >> p;
    for(int i=0;i<n;i++)cin >> a[i];
    sort(a,a+n);
    maxx = a[n-1];
    for(int i=0;i<n;i++){
        int c = 1;
        while(a[i] %p == 0){
            a[i] /= p;
            c++;
        }
        if(a[i] > 1)cost[c] = max(cost[c], a[i]);
    }
    if(cost.size() == 0){
        if(m < maxx){
            cout << 1 << endl;
        }else{
            cout << -1 << endl;
        }
        return 0;
    }
    cout << search(1) << endl;
}