Please help solve this probability question:
An airplane has 50 seats, and each of its 50 passengers shows up with his/her ticket that has assigned seat. The first person to enter the plane forgets to look at his ticker and chooses a seat on random. Each next person to enter the plane takes his assigned seat(if available or chooses a seat on random(if his/her seat his taken). What is the probability that the last passenger gets to sit in his assigned seat?