| # | Problem | Pass Rate (passed user / total user) |
|---|---|---|
| 11130 | Stack |
|
Description
Please implement the three basic stack operations.
Input
There are 3 kinds of stack operations(<50000) in the input, including
"push i": Push i on the stack, where i is an integer.
"pop": Pop the stack. Do nothing when the stack is empty.
"top": Output the top of the stack. Output "X" when the stack is empty.
Output
When a top operation is executed, output the top value of the stack.