use std::collections::HashSet;

fn main() {
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	let n: Vec<u8> = s.split_whitespace().flat_map(str::parse).collect();
	let s: HashSet<_> = n.iter().cloned().collect();
	let k = s.len();
	let t = n.iter().sum::<u8>();
	println!(
		"{}",
		match k {
			1 => n[0],
			2 => s.iter().sum::<u8>() * 2 - t,
			_ => 6 - t,
		}
	);
}