macro_rules! input { (source = $s:expr, $($r:tt)*) => { let mut iter = $s.split_whitespace(); input_inner!{iter, $($r)*} }; ($($r:tt)*) => { let mut 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, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } fn gcd(mut x:u64, mut y:u64) -> u64 { while y > 0 { x %= y; std::mem::swap(&mut x, &mut y); } x } fn main() { input!{ x: u64, y: u64 } let v = gcd(x, y); let mut ok:u64 = 0; let mut ng:u64 = 10000000000; while ng - ok > 1 { let mid = (ok + ng) / 2; if mid.pow(2) <= v { ok = mid; } else { ng = mid; } } println!("{}", if ok.pow(2) == v { "Odd" } else { "Even" }); }