Taco Expression Evaluator

Given a mathematical expression as a string composed of non-negative integers, binary operators (+, -, *, /), and parentheses ( and ), evaluate the expression following the standard operator precedence.

The division operator / uses integer division. In other words, if a and b are two non-negative integers, the expression

$$a \div b = \lfloor \frac{a}{b} \rfloor$$

For example, the expression 3+5*2 evaluates to 13.

You are expected to implement a solution using the algorithm based on stacks, which processes the operators and operands properly and respects the precedence and associativity rules.

inputFormat

The input consists of a single line containing a valid mathematical expression.

outputFormat

Output a single integer, the result of evaluating the expression.

## sample

3+5*2

13

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