def main():
    N, M = map(int, input().split())
    t, p = 0, 0
    for i in range(M):
        nt, np = map(int, input().split())
        if abs(t-nt) < abs(p-np):
            print('No')
            return
        t, p = nt, np
    print('Yes')


if __name__ == '__main__':
    main()