def check():
  N, M = map(int, input().split())
  T,P = [0]*(M+1),[0]*(M+1)
  for i in range(1,M+1):
    T[i],P[i] = map(int, input().split())
  for i in range(M):
    if abs(P[i+1]-P[i])>T[i+1]-T[i]:
      return 'No'
  return 'Yes'
print(check())