Constraint relation 02

Consider the situation shown in figure. Both the pulleys and the strings are light and all the surfaces are smooth. If acceleration of block of mass $2 \text{ kg}$ is $a_2$ and acceleration of block of mass $1\text{ kg}$ is $a_1$ . Then $a_1 = x \cdot a_2$ , where $x$ is an integer find the value of $x$ .