Fermat's Little Theorem Discrete Math

3. (6 points) Suppose Alice and Bob want to use Diffie-Hellman method with the published modulo p = 251 (which is a prime number) and base r = 3. Suppose their private components are a = 112 and b = 67. Use Fermat's little theorem to find their shared key. Note: no credit will be given if you do not use Fermat's little theorem