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 m = m+1;
    let maxval = *a.iter().max().unwrap();
    if maxval >= m {
        println!("1");
        return;
    }
    let paths = a.iter().map(|&v| costmap(v, p)).filter(|&v| v.0 > 1).collect::<Vec<_>>();
    if paths.is_empty() {
        println!("-1");
        return;
    }
    let mut cnt2val = vec![0usize; 31];
    for &(val, cnt) in paths.iter() {
        cnt2val[cnt] = cnt2val[cnt].max(val);
    }
    let mut dp = vec![vec![0usize; 1000]; 31];
    dp[0][1] = maxval;
    for cnt in 1..31 {
        for j in 0..1000 {
            dp[cnt][j] = dp[cnt][j].max(dp[cnt-1][j]).min(m);
            if j >= cnt {
                dp[cnt][j] = dp[cnt][j].max(dp[cnt][j-cnt] * cnt2val[cnt]).min(m);
            }
        }
    }
    println!("{}", (0..1000).filter(|&i| dp[30][i] == m).nth(0).unwrap());
}