use std::{
    collections::{BTreeSet, HashMap, HashSet, VecDeque},
    fmt::Debug,
    io::stdin,
    str::FromStr,
    sync::OnceLock,
};

use proconio::marker::Chars;

fn main() {
    proconio::input! {
        mut f0: u32,
        mut f1: u32,
        n:u64,
    }
    let fx = [f0, f1, f0 ^ f1];
    println!("{}", fx[(n % 3) as usize]);
}