#[allow(unused_imports)]
use std::cmp::*;
#[allow(unused_imports)]
use std::collections::*;
use std::io::{Write, BufWriter};
// https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    ($($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)*}
    };
}

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)*}
    };
}

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>>()
    };

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

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

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

fn gcd(mut x: i64, mut y: i64) -> i64 {
    while y != 0 {
        let r = x % y;
        x = y; y = r;
    }
    x
}

fn solve() {
    let out = std::io::stdout();
    let mut out = BufWriter::new(out.lock());
    macro_rules! puts {
        ($($format:tt)*) => (write!(out,$($format)*).unwrap());
    }
    input! {
        n: usize, k: usize,
    }
    const W: usize = 100_001;
    let mut fac = vec![0; W];
    for i in 2..W {
        if fac[i] != 0 {
            continue;
        }
        fac[i] = i;
        let mut j = 2 * i;
        while j < W {
            fac[j] = i;
            j += i;
        }
    }
    let mut faccnt = vec![0; W];
    let mut divcnt = vec![1; W];
    for i in 2..W {
        let mut v = i;
        while v > 1 {
            let p = fac[v];
            let mut e = 0;
            while v % p == 0 {
                v /= p;
                e += 1;
                faccnt[i] += 1;
            }
            divcnt[i] *= e + 1;
        }
    }
    let mut ma = (0, Reverse(0));
    for i in 1..n {
        let g = gcd(i as i64, n as i64) as usize;
        if faccnt[g] < k { continue; }
        ma = max(ma, (divcnt[i], Reverse(i)));
    }
    puts!("{}\n", (ma.1).0);
}

fn main() {
    // In order to avoid potential stack overflow, spawn a new thread.
    let stack_size = 104_857_600; // 100 MB
    let thd = std::thread::Builder::new().stack_size(stack_size);
    thd.spawn(|| solve()).unwrap().join().unwrap();
}