import sys; input = sys.stdin.buffer.readline
sys.setrecursionlimit(10**7)
from collections import defaultdict
con = 10 ** 9 + 7; INF = float("inf")

def getlist():
	return list(map(int, input().split()))

#処理内容
def main():
	N, M = getlist()
	itr = 0
	time = 0
	for i in range(M):
		T, P = getlist()
		if abs(P - itr) > T - time:
			print("No")
			return
		time = T
		itr = P

	print("Yes")




if __name__ == '__main__':
	main()