import java.util.HashMap;
import java.util.Map;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int range = sc.nextInt();
		int infoNum = sc.nextInt();
		Map<Integer, Integer> info = new HashMap<>();
		for (int i = 0; i < infoNum;) {
			info.put(sc.nextInt(), sc.nextInt());
			i++;
		}
		int key1 = 0;
		int value1 = 0;
		int key2 = 0;
		int value2 = 0;
		String judgement = "Yes";
		for(Integer key : info.keySet()) {
			key2 = key;
			value2 = info.get(key);
			if(Math.abs(key2 - key1) < Math.abs(value2 - value1)) {
				judgement = "No";
				break;
			}
			key1 = key2;
			value1 = value2;
		}
		System.out.println(judgement);
	}
}