13. (6 points) Squirrels $A$, $B$, and $C$ have a total of some pine nuts. Squirrel $A$ originally had 26 pine nuts, from which it took out 10 pine nuts and divided them equally between $B$ and $C$. Then, Squirrel $B$ took out 18 of its own pine nuts and divided them equally between $A$ and $C$. Finally, Squirrel $C$ divided half of its current pine nuts equally between $A$ and $B$. At this point, the three squirrels have the same number of pine nuts. How many pine nuts did Squirrel $C$ originally have? $\qquad$
【Answer】Solution: $10 \div 2=5$ (nuts)
$18 \div 2=9$ (nuts)
At this point, $A$ has: $26-10+9=25$ (nuts)
At this point, $C$ has: $25 \times 4=100$ (nuts)
Originally, $C$ had: $100-9-5=86$ (nuts)
Answer: Squirrel $C$ originally had 86 nuts.
Therefore, the answer is: 86.