def solve():
    N, M = list(map(int, input().split()))
    a = [0] * M
    for _ in range(N):
        l, r = list(map(int, input().split()))
        for i in range(l, r + 1):
            a[i] += 1
            a[-1 - i] += 1

    print('YES' if all(ai <= 2 for ai in a) else 'NO')


if __name__ == '__main__':
    solve()