Stack 2

Implement a stack that stores integers, then write a program that processes the commands given as input. There are five commands.

1. 1 X: Push the integer X onto the stack. (1 ≤ X ≤ 100,000)
2. 2: If the stack has an integer, remove the top integer and print it. Otherwise, print -1.
3. 3: Print the number of integers in the stack.
4. 4: Print 1 if the stack is empty, otherwise print 0.
5. 5: If the stack has an integer, print the top integer. Otherwise, print -1.

The first line contains the number of commands N (1 ≤ N ≤ 1,000,000). The next N lines each contain one command. At least one command asks for output.

Each time a command that requires output is given, print its result on its own line.