func main()
	var n: int :: cui@inputInt()
	var m: int :: cui@inputInt()
	var ans: bool :: true
	var currentP: int :: 0
	var currentT: int :: 0
	for i(0, m - 1)
		var t: int :: cui@inputInt()
		var p: int :: cui@inputInt()
		if((p - currentP).abs() > t - currentT)
			do ans :: false
			break i
		end if
		do currentT :: t
		do currentP :: p
	end for
	do cui@print(ans ?("Yes\n", "No\n"))
end func