use std::io::*;
const INF: usize = 1 << 30;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let m: usize = itr.next().unwrap().parse().unwrap();
    let p: usize = itr.next().unwrap().parse().unwrap();
    let a: Vec<usize> = (0..n)
        .map(|_| itr.next().unwrap().parse().unwrap())
        .collect();

    let mut max = 0;
    let mut b = Vec::new();
    for &e in a.iter() {
        max = std::cmp::max(max, e);
        let mut cnt = 1;
        let mut x = e;
        while x % p == 0 {
            x /= p;
            cnt += 1;
        }
        if x == 1 {
            continue;
        }
        b.push((cnt, x));
    }
    b.sort();

    if max > m {
        println!("1");
    } else {
        let mut dp = vec![0; 100];
        dp[0] = 1;
        for &(cnt, x) in b.iter() {
            for i in 0..100 {
                if dp[i] > m || cnt + i >= 100 {
                    break;
                }
                dp[i + cnt] = std::cmp::max(dp[i + cnt], dp[i] * x);
            }
        }

        let mut ans = INF;
        for i in 1..100 {
            if dp[i] > m {
                ans = std::cmp::min(ans, i);
            }
        }
        if ans == INF {
            println!("-1");
        } else {
            println!("{}", ans);
        }
    }
}