use std::cmp::min;

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

    let l: usize = lrm[0];
    let r: usize = lrm[1];
    let m: usize = lrm[2];

    let result = min(r+1, l+m) - l;
    println!("{}", result);
}