n, m = map(int, input().split())

time, now = 0, 0

flg = True
for i in range(m):
    t, p = map(int, input().split())
    if p - now > t - time:
        flg = False
        break
    else:
        time = t
        now = p

if flg:
    print('Yes')
else:
    print('No')