What is the molarity of the NaOH solution in the Question below?

A chemist weighed out 0.5276 grams of KHP and disolved it in in about 50 mL of distilled H2O and added a drop of phenolphthalein indicator. A 50mL buret was filled with an unknown strength of NaOH solution. The initial Volume of the buret was read at 12.83 mL. The NaOH solution was carefully added to the KHP solution until a permanent very slight pink coloration was noticed. The buret was read again and recorded as 35.26 mL. Calculate the molarity of the NaOH solution.