N,M = map(int,input().split())
info = []
for _ in range(M):
    t,p = map(int,input().split())
    info.append((t,p))

time = 0
pos = 0
import sys
for t,p in info:
    if time > t:
        print('No')
        exit()
    delta = t - time
    deltapos = abs(p-pos)
    if deltapos > delta:
        print('No')
        exit()
    time = t
    pos = p
print('Yes')