use std::collections::{HashMap, HashSet};

const INF: usize = 1usize << 60;

fn gcd(a: usize, b: usize) -> usize {
    if b == 0 { return a; }
    gcd(b, a%b)
}

fn main() {
    let mut nmp = String::new();
    std::io::stdin().read_line(&mut nmp).ok();
    let nmp: Vec<usize> = nmp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = nmp[0];
    let m = nmp[1];
    let p = nmp[2];
    let mut a = String::new();
    std::io::stdin().read_line(&mut a).ok();
    let a: Vec<usize> = a.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();

    if m == 1 {
        println!("0");
        return;
    }
    let maxval = *a.iter().max().unwrap();
    if maxval >= m {
        println!("1");
        return;
    }
    let mut a = a.into_iter()
        .map(|v| {
            let mut ret = v;
            while ret % p == 0 {
                ret /= p;
            }
            ret
        })
        .filter(|&v| v > 1)
        .collect::<HashSet<_>>()
        .into_iter()
        .collect::<Vec<usize>>();
    if p == 1 || a.is_empty() {
        println!("-1");
        return;
    }
    a.sort();
    a.reverse();
    let mut start_val = 1usize;
    let mut cnt = 0usize;
    for &v in a.iter() {
        for _ in 1.. {
            if start_val * v * maxval >= m {
                println!("{}", cnt+2);
                return;
            }
            if start_val * v % p == 0 {
                break;
            }
            start_val *= v;
            cnt += 1;
        }
    }
    println!("-1");
}