N, M = map(int, input().split())
TP = [list(map(int, input().split())) for _ in range(M)]
BT = 0
BP = 0
for T, P in TP:
    DIST = abs(P - BP)
    if DIST > T - BT:
        print("No")
        exit(0)
    BT = T
    BP = P
print("Yes")