use std::cmp::max;
use std::io::*;

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: u64 = itr.next().unwrap().parse().unwrap();
    let m = n * (n + 1) / 2;

    let mut ans = 0;
    let mut i = 1;
    while i * i <= m {
        if m % i == 0 {
            if i <= n {
                ans = max(ans, i);
            }
            if m / i <= n {
                ans = max(ans, m / i)
            }
        }
        i += 1;
    }
    println!("{}", ans);
}