Complete the following table of values of a function

$\varphi: \lbrace 9,10,...,17,18 \rbrace \rightarrow \lbrace 8,9,...,16,17 \rbrace$

$x$	9	10	11	12	13	14	15	16	17	18
$\varphi(x)$	12			8	11	16			13

so that $\varphi$ is onto.