use std::collections::*; 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 ask(a: usize, b: usize) -> i32 { println!("{} {}", a + 1, b + 1); let s = get_word(); if s == "Black" { 1 } else if s == "White" { 0 } else { panic!(); } } fn main() { let n: usize = get(); let _m: usize = get(); let mut col = vec![vec![2; n]; n]; col[0][0] = 1; col[n - 1][n - 1] = 1; let mut que = VecDeque::new(); que.push_back((0, 0)); let dxy = [(0i32, 1i32), (1, 0), (0, -1), (-1, 0)]; let mut vis = vec![vec![false; n]; n]; while let Some((x, y)) = que.pop_front() { if vis[x][y] { continue; } vis[x][y] = true; for &(dx, dy) in &dxy { let nx = (x as i32 + dx) as usize; let ny = (y as i32 + dy) as usize; if nx >= n || ny >= n { continue; } if col[nx][ny] == 2 { col[nx][ny] = ask(nx, ny); } if col[nx][ny] == 1 { que.push_back((nx, ny)); } } } println!("{}", if vis[n - 1][n - 1] { "Yes" } else { "No" }); }