use std::cmp::min;

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();

    let mut result = if n > 4 && n % 2 == 0 { n / 2 } else { n };
    for i in 3..=min(result, 1000000) {
        if n % i == 0 {
            result = i;
            break;
        }
    }
    println!("{}", result);
}