n, m = map(int, input().split())
a, b = 0, 0
tp = [list(map(int, input().split())) for i in range(m)]
for i in range(m):
    if abs(tp[i][1] - a) > tp[i][0] - b:
        exit(print("No"))
    a, b = tp[i][1], tp[i][0]
print("Yes")