import java.util.*;

public class Main {
    static final int MOD = 1000000007;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        long prevT = 0;
        int prevP = 0;
        for (int i = 0; i < m; i++) {
            long t = sc.nextLong();
            int p = sc.nextInt();
            if (t - prevT < Math.abs(p - prevP)) {
                System.out.println("No");
                return;
            }
            prevT = t;
            prevP = p;
        }
        System.out.println("Yes");
    }
}