A pendulum set up in the stairwell of a 14 story building

Question

Problem: A pendulum set up in the stairwell of a 14 story building consists of a heavy weight suspended on a 25.5 m wire. If g = 9.81 m/s²,

Part A: What is the period of oscillation?

............ s

Show how you get the answer, so that I can better understand how to do it.