fn main() {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    let input: Vec<i32> = s.trim().split_whitespace().map(|e| e.parse().unwrap()).collect();

    let l = input[0];
    let r = input[1];
    let m = input[2];
    let w = r - l + 1;
    let cnt = if w < m { w } else { m };
    println!("{}", cnt);
}