// ---------- begin input macro ---------- // reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 macro_rules! input { (source = $s:expr, $($r:tt)*) => { let mut iter = $s.split_whitespace(); input_inner!{iter, $($r)*} }; ($($r:tt)*) => { let s = { use std::io::Read; let mut s = String::new(); std::io::stdin().read_to_string(&mut s).unwrap(); s }; let mut iter = s.split_whitespace(); input_inner!{iter, $($r)*} }; } macro_rules! input_inner { ($iter:expr) => {}; ($iter:expr, ) => {}; ($iter:expr, $var:ident : $t:tt $($r:tt)*) => { let $var = read_value!($iter, $t); input_inner!{$iter $($r)*} }; } macro_rules! read_value { ($iter:expr, ( $($t:tt),* )) => { ( $(read_value!($iter, $t)),* ) }; ($iter:expr, [ $t:tt ; $len:expr ]) => { (0..$len).map(|_| read_value!($iter, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, bytes) => { read_value!($iter, String).bytes().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } // ---------- end input macro ---------- fn run() { input! { n: usize, a: [usize; n], } let w = std::mem::size_of::() * 8; let mut sum = 0; let mut dp = vec![1usize]; for a in a { sum += a; let mut next = vec![0; sum / w + 2]; next[..dp.len()].copy_from_slice(&dp); let q = a / w; let r = a % w; if r == 0 { for (next, dp) in next[q..].iter_mut().zip(dp.iter()) { *next ^= *dp; } } else { for (i, dp) in dp.iter().enumerate() { next[i + q] ^= *dp << r; next[i + q + 1] ^= *dp >> (w - r); } } dp = next; dp.truncate(sum / w + 1); } let mut ans = 0; for i in 0..=sum { ans ^= (dp[i / w] >> i & 1) * i; } println!("{}", ans); } fn main() { run(); }