1. Given sets $A = \{ 1,3 , m \} , B = \{ 3,4 \} , A \cup B = \{ 1,2,3,4 \}$ , then $m =$ $\_\_\_\_$ .
(5 points) Given sets $A = \{ x | | x | \leqslant 2 , x \in \mathbb{R} \} , B = \{ x \mid \sqrt { x } \leqslant 4 , x \in \mathbb{Z} \}$, then $A \cap B =$
1. Given sets $A = \{ 1,3 , m \} , B = \{ 3,4 \} , A \cup B = \{ 1,2,3,4 \}$ , then $m =$ $\_\_\_\_$ .\\