N, M = map(int, input().split())

pret, prepos = 0, 0
for i in range(M):
    t, p = map(int, input().split())
    diff = t - pret
    
    # prepos --> p への移動
    if diff >= abs(p - prepos):
        continue
    else:
        exit(print('No'))
    
    prepos = p
    pret = t

print('Yes')