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


fn costmap(val: usize, p: usize) -> (usize, usize) {
    let mut cnt = 1usize;
    let mut val = val;
    while val % p == 0 {
        cnt += 1;
        val /= p;
    }
    (val, cnt)
}

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();

    let maxval = *a.iter().max().unwrap();
    if maxval >= m {
        println!("1");
        return;
    }
    let mut paths = a.iter().map(|&v| costmap(v, p)).filter(|&v| v.0 > 1).collect::<Vec<_>>();
    if paths.is_empty() {
        println!("-1");
        return;
    }
    paths.sort();
    paths.reverse();
    let mut npaths = HashMap::new();
    for &(val, cnt) in paths.iter() {
        npaths.insert(val, cnt);
    }
    let mut result = 1usize << 60;
    let mut dp = HashMap::new();
    dp.insert(maxval, 1usize);
    let mut deque = VecDeque::new();
    deque.push_back((maxval, 1usize));
    while let Some((val, cnt)) = deque.pop_front() {
        let mut updated_keys = HashSet::new();
        for (&aval, &acnt) in npaths.iter() {
            if let Some(&ccnt) = dp.get(&(val + aval)) {
                if ccnt > cnt + acnt && val + aval < m {
                    dp.insert(val*aval, cnt+acnt);
                    updated_keys.insert(val*aval);
                }
            } else if val*aval < m {
                dp.insert(val*aval, cnt+acnt);
                updated_keys.insert(val*aval);
            }
            if val * aval >= m {
                result = result.min(cnt+acnt);
            }
        }
        for v in updated_keys.iter() {
            deque.push_back((*v, *dp.get(v).unwrap()));
        }
    }
    println!("{}", result);
}