n, m = map(int, input().split())
lr = [tuple(map(int, input().split())) for _ in range(n)]

used = [False] * m
for i in range(n):
    ok = True
    for j in range(m):
        if lr[i][0] <= j <= lr[i][1] and used[j]:
            ok = False

    if ok:
        for j in range(m):
            if lr[i][0] <= j <= lr[i][1]:
                used[j] = True
        continue

    ok = True
    for j in range(m):
        if m - 1 - lr[i][1] <= j <= m - 1 - lr[i][1] and used[j]:
            ok = False

    if ok:
        for j in range(m):
            if m - 1 - lr[i][1] <= j <= m - 1 - lr[i][1]:
                used[j] = True

        continue

    print("NO")
    exit()


print("YES")