#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long long a[200020];
int main() {
    long long n, m, p;
    cin >> n >> m >> p;
    long long ans = 1, co1;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        int co2 = 1;
        while (a[i] % p == 0) {
            a[i] /= p;
            co2++;
        }
        if (ans < a[i]) {
            ans = a[i];
            co1 = co2;
        }
    }
    if (ans == 1) {
        cout << "-1" << endl;
    }
    else {
        int co = 0;
        while (m >= 1) {
            m /= ans;
            co++;
        }
        cout << co * co1 << endl;
    }
}