fn run() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).unwrap();
    let mut it = s.trim().split_whitespace();
    let n: i64 = it.next().unwrap().parse().unwrap();
    let k: i64 = it.next().unwrap().parse().unwrap();
    let ans = if k < n - k {
        k + 1
    } else if n % 2 == 0 {
        n / 2
    } else {
        std::cmp::min(k + 1, n)
    };
    println!("{}", ans);
}

fn main() {
    run();
}