#include <bits/stdc++.h>

//#include <atcoder/all>
#define For(i, a, b) for (int(i) = (int)(a); (i) < (int)(b); ++(i))
#define rFor(i, a, b) for (int(i) = (int)(a)-1; (i) >= (int)(b); --(i))
#define rep(i, n) For((i), 0, (n))
#define rrep(i, n) rFor((i), (n), 0)
#define fi first
#define se second
using namespace std;
typedef long long lint;
typedef unsigned long long ulint;
typedef pair<int, int> pii;
typedef pair<lint, lint> pll;
template <class T>
bool chmax(T &a, const T &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
bool chmin(T &a, const T &b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template <class T>
T div_floor(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a >= 0 ? a / b : (a + 1) / b - 1;
}
template <class T>
T div_ceil(T a, T b) {
    if (b < 0) a *= -1, b *= -1;
    return a > 0 ? (a - 1) / b + 1 : a / b;
}

constexpr lint mod = 1000000007;
constexpr lint INF = mod * mod;
constexpr int MAX = 200010;

int main() {
    int n;
    lint m, p;
    scanf("%d%lld%lld", &n, &m, &p);
    lint a[n];
    rep(i, n) scanf("%lld", &a[i]);

    lint b = *max_element(a, a + n);
    if (b > m) {
        printf("%d\n", 1);
        return 0;
    }
    int ans = -1;
    rep(i, n) {
        int cnt = 1;
        lint t = a[i];
        while (t % p == 0) {
            ++cnt;
            t /= p;
        }
        if (t == 1) continue;

        int tmp = 1;
        lint x = 1;
        while (x * b <= m) {
            tmp += cnt;
            x *= t;
        }
        if (ans == -1 || ans > tmp) ans = tmp;
    }
    printf("%d\n", ans);
}