What value should be the variable index 'idx' in the code below so that the expression

$","```$python

$",$"sorted$($number$\_$list$)[$idx$]$

$","```$

$","...$ does the same thing. $($i$.$e$.,$ when you run the cell, it should display $20.)$

$",$"hint: $`$idx$`$ is a $**$negative$**$ integer."$]\},\{"$cell$\_$type":"code","execution$\_$count":null,"metadata":$\{"$id$"$:"rVeIWaSB$8$eau"$\},$"outputs":$[],$"source":$["$idx $=?$