use std::cmp;
fn main() {
    let mut nk = String::new();
    std::io::stdin().read_line(&mut nk).ok();
    let mut nk = nk.trim().split_whitespace();
    let n: u64 = nk.next().unwrap().parse().unwrap();
    let k: u64 = nk.next().unwrap().parse().unwrap();

    if n % 2 == 0 { println!("{}", cmp::min(n / 2, 1 + k)); }
    else { println!("{}", cmp::min(n, 1 + k)); }
}