n,m=map(int,input().split())
numt=0
nump=0
ans=0
for i in range(m):
    t,p=map(int,input().split())
    if abs(nump-p)>t-numt:
        ans=1
        break
    nump=p
    numt=t
if ans==1:
    print("No")
else:
    print("Yes")