Evaluate Prefix Expression

You are given an arithmetic expression in prefix notation. In this notation, every operator precedes its operands. The allowed operators are \(+\), \(-\), \(\times\), and \(\div\). The division operator performs integer division (i.e. the result of \(\frac{a}{b}\) is truncated towards zero).

Your task is to evaluate the given prefix expression and output the resulting integer.

Example:

Input: + 1 2
Output: 3

inputFormat

The input consists of a single line containing a valid prefix expression. The tokens (operators and operands) are separated by spaces.

outputFormat

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

+ 1 2

3