N, M = map(int, input().split())
TP = [list(map(int, input().split())) for i in range(M)]
if TP[0][0] < TP[0][1]:
    print("No")
    exit()
for i in range(1, M):
    if abs(TP[i][0] - TP[i - 1][0]) < abs(TP[i][1] - TP[i - 1][1]):
        print("No")
        exit()
print("Yes")