Evaluate Postfix Expression
Evaluate an expression in Reverse Polish (postfix) notation, e.g. 2 1 + 3 * = . Division truncates toward zero. All intermediate values fit in 32-bit integers.
Input
One line of tokens separated by spaces.
Output
The value.
Constraints
At most tokens.
Sample 1
Input
2 1 + 3 *
Output
9
Sample 2
Input
4 13 5 / +
Output
6