What is printed by the following statements?

mydict $=\{"$cat$"$:$12,$ "dog":$6,$ "elephant":$23\}$

mydict$["$mouse$"]=$ mydict$["$cat$"]+$ mydict$["$dog$"]$

print$($mydict$["$mouse$"])$

Group of answer choices

$12$

Runtime error, there is no entry with 'mouse' as the key

$0$

$18$