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

pret, prepos = 0, 0
ans = 'Yes'
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):
        prepos = p
        pret = t
    else:
        exit(print('No'))

print('Yes')