fn main() {
    let mut nm = String::new();
    std::io::stdin().read_line(&mut nm).ok();
    let nm: Vec<i32> = nm.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let m = nm[1];
    let mut pos: i32 = 0;
    let mut result = true;
    let mut prev = 0i64;
    for _ in 0..m {
        let mut tp = String::new();
        std::io::stdin().read_line(&mut tp).ok();
        let tp: Vec<i64> = tp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
        let t = tp[0];
        let p = tp[1] as i32;
        if t - prev >= (p - pos).abs() as i64 {
            pos = p;
            prev = t;
        } else {
            result = false;
        }
    }
    println!("{}", if result { "Yes" } else { "No" });
}