Evaluate Mathematical Expression

You are given a string expr representing a mathematical expression. This expression contains non-negative integers, plus signs (+), minus signs (-), and parentheses.

Your task is to evaluate the expression and output its numerical result.

The expression should be evaluated according to the standard rules of arithmetic: parentheses first, then left-to-right evaluation for + and - operators. All numbers in the expression are non-negative integers and may have multiple digits. Note that the expression may include spaces.

For example, given the expression: 6 - (4 - (2 + 3)), the evaluation should return 7.

inputFormat

The input consists of a single line containing the expression expr. The expression may contain spaces, digits, '+', '-', and parentheses '('.

outputFormat

Output a single integer which is the result of evaluating the expression.

1 + 2

3