n,m = map(int,input().split())
sw = 1
x = 0
t0 = 0
for i in range(m):
    t,p = map(int,input().split())
    if abs(p-x) <= t - t0:
        x = p
        t0 = t
    else:
        sw = 0
        break
        
print(["No","Yes"][sw])