#![allow(unused_macros, unused_imports, dead_code)]
use std::any::TypeId;
use std::cmp::{max, min, Reverse};
use std::collections::{BTreeMap, BTreeSet, BinaryHeap, HashMap, HashSet, VecDeque};
use std::mem::swap;
use std::ops::{Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Rem, Sub, SubAssign};

mod procon_reader {
    use std::fmt::Debug;
    use std::io::Read;
    use std::str::FromStr;
    pub fn read<T: FromStr>() -> T
    where
        <T as FromStr>::Err: Debug,
    {
        let stdin = std::io::stdin();
        let mut stdin_lock = stdin.lock();
        let mut u8b: [u8; 1] = [0];
        loop {
            let mut buf: Vec<u8> = Vec::with_capacity(16);
            loop {
                let res = stdin_lock.read(&mut u8b);
                if res.unwrap_or(0) == 0 || u8b[0] <= b' ' {
                    break;
                } else {
                    buf.push(u8b[0]);
                }
            }
            if !buf.is_empty() {
                let ret = String::from_utf8(buf).unwrap();
                return ret.parse().unwrap();
            }
        }
    }
    pub fn read_vec<T: std::str::FromStr>(n: usize) -> Vec<T>
    where
        <T as FromStr>::Err: Debug,
    {
        (0..n).map(|_| read::<T>()).collect::<Vec<T>>()
    }
    pub fn read_vec_sub1(n: usize) -> Vec<usize> {
        (0..n).map(|_| read::<usize>() - 1).collect::<Vec<usize>>()
    }
    pub fn read_mat<T: std::str::FromStr>(h: usize, w: usize) -> Vec<Vec<T>>
    where
        <T as FromStr>::Err: Debug,
    {
        (0..h).map(|_| read_vec::<T>(w)).collect::<Vec<Vec<T>>>()
    }
}
use procon_reader::*;
/*************************************************************************************
*************************************************************************************/

fn main() {
    let mut n = read::<usize>() - 1;
    let mut unit = 0;
    for b in 1..10 {
        for a in 1..b {
            unit += 1;
        }
    }
    let unit = unit;
    let c = n / unit;
    n %= unit;
    let mut cnt = 0;
    for a in 1..10 {
        for b in 1..10 {
            if a >= b {
                continue;
            }
            if cnt == n {
                let mut x = (10 * a + b).to_string();
                for _ in 0..c {
                    x.push((b as u8 + b'0') as char)
                }
                println!("{}", x);
                return;
            }
            cnt += 1;
        }
    }
}