### Problem Statement

A simple calculator accepts the following kinds of strings as input:
• 1) NUM+NUM
• 2) NUM-NUM
• 3) NUM*NUM
• 4) NUM/NUM
where NUM is a positive integer, between 1 and 10000 inclusive that can contain leading zeros. Return the value produced by the given expression. Here +,-,*, and / denote addition, subtraction, multiplication and division respectively. All operations are done on integers, so "5/3" returns 1.

### Definition

 Class: SimpleCalculator Method: calculate Parameters: String Returns: int Method signature: int calculate(String input) (be sure your method is public)

### Constraints

-input will contain between 3 and 50 characters inclusive.
-input will have the form <NUM><OP><NUM> where

<NUM> is a positive integer between 1 and 10000 inclusive, that may contain leading zeros and

<OP> is one of (quotes for clarity) '+','*','-', or '/'.
-input will not contain any spaces.

### Examples

0)

 `"5/3"`
`Returns: 1`
 Remember integer division is used, so results are truncated.
1)

 `"15*3"`
`Returns: 45`
2)

 `"1-10000"`
`Returns: -9999`
 Negative results are allowed.
3)

 `"17+18"`
`Returns: 35`
4)

 `"0000000000000018/00000000000000000009"`
`Returns: 2`
 The long way of writing 18/9.

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=2272

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=4710&pm=2272

brett1479

#### Testers:

lbackstrom , schveiguy

String Parsing