use std::io::Read; fn get_word() -> String { let stdin = std::io::stdin(); let mut stdin=stdin.lock(); let mut u8b: [u8; 1] = [0]; loop { let mut buf: Vec = Vec::with_capacity(16); loop { let res = stdin.read(&mut u8b); if res.unwrap_or(0) == 0 || u8b[0] <= b' ' { break; } else { buf.push(u8b[0]); } } if buf.len() >= 1 { let ret = String::from_utf8(buf).unwrap(); return ret; } } } #[allow(dead_code)] fn get() -> T { get_word().parse().ok().unwrap() } fn main() { let n: usize = get(); let m: usize = get(); let nn = n as i64; let nn2 = nn / 2; if m < n - 1 || m as i64 > nn2 * (nn - nn2) { println!("NO"); return; } let mut x = 1; while x < nn / 2 && x * (nn - x) < m as i64 { x += 1; } println!("YES"); for i in 0..n { print!("{}{}", i + 1, if i + 1 == n { "\n" } else { " " }); } let x = x as usize; for i in 0..m { println!("{} {}", i / (n - x) + 1, x + 1 + i % (n - x)); } }