Add:station 2
Add:stack
Add:station 1
Add:stack
Top:stack
Remove:stack
Remove:station
Stack
Size:stack
Train
Remove:stack
Remove:station
Stack
Size:stack
Train
Add:station 4
Add:stack
Add:station 3
Add:stack
Top:stack
Remove:stack
Remove:station
Stack
Size:stack
Train
Remove:stack
Remove:station
Add:stack
Stack
Size:stack
Train