n,m = map(int,input().split())
x = 0
y = 0
flg = True
for i in range(m):
    t,p = map(int,input().split())
    a = t-x
    b = abs(p-y)
    if b > a:
        flg = False
    x = t
    y = p
if flg:
    print('Yes')
else:
    print('No')