N,M=map(int,input().split())
Old_T=0
Old_P=0

F=True
for _ in range(M):
    T,P=map(int,input().split())
    F&=(abs(P-Old_P)<=T-Old_T)
    Old_T,Old_P=T,P
if F:
    print("Yes")
else:
    print("No")