Stack

Implement a stack of integers and process the commands from the input in order.

There are five commands.

• push X: put the integer $X$ on the stack.
• pop: remove the integer on top of the stack and print it. Print $-1$ when the stack is empty.
• size: print how many integers the stack holds.
• empty: print $1$ when the stack is empty, otherwise $0$.
• top: print the integer on top of the stack. Print $-1$ when the stack is empty.

The first line holds the number of commands $N$ ($1 \le N \le 10000$). Each of the next $N$ lines holds one command. The integer $X$ of a push command satisfies $1 \le X \le 100000$. No command outside the list above is given.

For every command that prints something, print its result on its own line, in the order the commands are given.