Sets, Relations and Functions: JEE Main 2020 Mathematics question

Let X = {n $\in$ N : 1 $\le$ n $\le$ 50}. If A = {n $\in$ X: n is a multiple of 2} and B = {n $\in$ X: n is a multiple of 7}, then the number of elements in the smallest subset of X containing both A and B is ________.