n, m = map(int, input().split())
tp = [tuple(map(int, input().split())) for _ in range(m)]
tp.sort()
now = 0
pos = 0
for i in range(m):
    t, p = tp[i]
    if t - now < p - pos:
        print("No")
        exit()
    now, pos = t, p
print("Yes")