A person walks along a train at a constant speed while the train is moving. When walking from the back of the train to the front, in the direction of the train's motion, the person counts steps. When walking from the front of the train to the back, against the train's motion, the person counts steps. If the person's speed relative to the ground is faster than the train's speed, what is the length of the train in terms of the person's steps?
80
85
90
95
100
