import sys
def input(): return sys.stdin.readline().strip()
def mapint(): return map(int, input().split())
sys.setrecursionlimit(10**9)

N, M = mapint()
now, time = 0, 0
for _ in range(M):
    t, p = mapint()
    if t-time<abs(now-p):
        print('No')
        break
    now, time = p, t
else:
    print('Yes')