Given the complete set L = {x | x ∈ r}, set a = {x, X less than or equal to 1 or X ≥ 3}, set B = {x, K < x < K + 1, K ∈ r} and (C1a) ∩ B = empty set, then the value range of real number k is

Given the complete set L = {x | x ∈ r}, set a = {x, X less than or equal to 1 or X ≥ 3}, set B = {x, K < x < K + 1, K ∈ r} and (C1a) ∩ B = empty set, then the value range of real number k is

k【1,3】