use std::io;

fn main() {
    let nm: Vec<u32> = {
        let mut s = String::new();
        io::stdin().read_line(&mut s);
        s.trim().split_whitespace().map(|x| x.parse().unwrap()).collect()
    };
    let n = nm[0];
    let m = nm[1];
    let k: u32 = {
        let mut s = String::new();
        io::stdin().read_line(&mut s);
        s.trim().parse().unwrap()
    };
    let mut a: Vec<u32> = {
        (1..n).into_iter().map(|_| {
            let mut s = String::new();
            io::stdin().read_line(&mut s);
            s.trim().parse().unwrap()
        }).collect()
    };
    a.sort();

    let f = |i| {
        let us = k + a[i];
        let mut gt_us = 0;
        let mut tail = a.len() - 1;
        if tail == i {
            tail -= 1;
        }
        for head in 0..a.len() {
            if head == i {
                continue;
            }
            if head >= tail {
                break;
            }
            if a[head] + a[tail] > us {
                gt_us += 1;
                if gt_us >= m {
                    break;
                }
                tail -= 1;
                if tail == i {
                    tail -= 1;
                }
                continue;
            }
        }
        if gt_us < m {
            return a[i] as i32;
        }
        return -1;
    };
    if f(a.len() - 1) == -1 {
        println!("-1");
        return;
    }
    {
        let t = f(0);
        if t != -1 {
            println!("{}", a[0]);
            return;
        }
    }
    let mut head = 0;
    let mut tail = a.len() - 1;
    loop {
        let x = (head + tail) / 2;
        if tail - head < 2 {
            println!("{}", a[tail]);
            return;
        }
        let y = f(x);
        if y <= 0 {
            head = x;
        }
        else {
            tail = x;
        }
    }
}