#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };

    ($next:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, bytes) => {
        read_value!($next, String).into_bytes()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}

fn main() {
    input! {
        n: usize,
        jj: usize,
        v: usize,
        p: usize,
        mut a: [usize; n],
    }

    a.sort();
    // dbg!(&a);

    let mut l = -1_i64;
    let mut r = (n - 1) as i64;

    while (r - l) > 1 {
        let m = (l + r) as usize / 2;

        let check = |m: usize| -> bool {
            if m >= n - p {
                true
            } else {
                let mut t = a.clone();

                if m < v {
                    let mut rest = v;
                    for i in 0..m + 1 {
                        t[i] += jj;
                        rest -= 1;
                    }

                    for i in (0..n).rev().take(p - 1) {
                        if rest == 0 {
                            break;
                        }
                        t[i] += jj;
                        rest -= 1;
                    }

                    // [m+1 .. n-p+1) の間に m*rest個入れる
                    // dbg!(rest, &t);
                    if rest > 0 {
                        let mut rest = rest * jj;
                        for i in m + 1..m + 1 + (n - (m + 1) - (p - 1)) {
                            if rest <= 0 {
                                break;
                            }
                            if t[m] > t[i] {
                                let uu = std::cmp::min(rest, t[m] - t[i]);
                                rest -= uu;
                                t[i] += uu;
                            }
                        }
                        if rest > 0 {
                            return false;
                        }
                    }
                } else {
                    for i in 0..v - 1 {
                        t[i] += jj;
                    }
                    t[m] += jj;
                }

                // dbg!(&t);

                let mut up = 0;
                for i in 0..n {
                    if t[i] > t[m] {
                        up += 1;
                    }
                }

                up < p
            }
        };

        // dbg!(m, check(m));

        if check(m) {
            r = m as i64;
        } else {
            l = m as i64;
        }
    }

    let border = a[r as usize];

    // dbg!(r, border);

    let ans = a.iter().filter(|&&a| a >= border).count();

    println!("{}", ans);
}


Measured memory_bytes: 7908