pub mod io {
    use std::io::{BufRead, ErrorKind};

    pub fn scan<R: BufRead>(r: &mut R) -> String {
        let mut res = Vec::new();
        loop {
            let buf = match r.fill_buf() {
                Ok(buf) => buf,
                Err(e) if e.kind() == ErrorKind::Interrupted => continue,
                Err(e) => panic!(e), 
            };
            let (done, used, buf) = {
                match buf.iter().position(u8::is_ascii_whitespace) {
                    Some(i) => (i | res.len() > 0, i + 1, &buf[..i]),
                    None => (buf.is_empty(), buf.len(), buf),
                }
            };
            res.extend_from_slice(buf);
            r.consume(used);
            if done {
                return String::from_utf8(res).unwrap();
            }
        }
    }

    #[macro_export]
    macro_rules! scan {
        ($r:expr) => (io::scan(&mut $r));
        ($r:expr, $($t:ty),*) => (($(scan!($r).parse::<$t>().unwrap()),*));
    }
}

fn main() {
    let stdin = std::io::stdin();
    let mut reader = std::io::BufReader::new(stdin.lock());
    
    let k = scan!(reader, u64);
    let n = 2 * k - 1;

    let ans = n * n + 2 * (n + 1) + (n + 2) / 2 - (k - 1);
    println!("{}", ans);
}