### Problem Statement

Consider the following set (see notes for clarification):
```  S = {  p/q  |   w <= p <= x,  y <= q <= z  }
```
Given w, x, y, and z return the number of distinct elements in S.

### Definition

 Class: FractionCounting Method: howMany Parameters: int, int, int, int Returns: int Method signature: int howMany(int w, int x, int y, int z) (be sure your method is public)

### Notes

-S is the set of all rational numbers whose numerators are between w and x inclusive, and whose denominators are between y and z inclusive.

### Constraints

-x and z will be between 1 and 100, inclusive.
-w will be between 1 and x, inclusive.
-y will be between 1 and z, inclusive.

### Examples

0)

 `1` `1` `1` `1`
`Returns: 1`
 Only the value 1/1 is being considered.
1)

 `1` `10` `1` `1`
`Returns: 10`
 Here S contains the values 1,...,10.
2)

 `1` `2` `1` `2`
`Returns: 3`
 Here the values are 1/1, 1/2, 2/1, and 2/2. Since 2/2 = 1/1 the answer is 3.
3)

 `2` `4` `2` `4`
`Returns: 7`
4)

 `1` `100` `1` `100`
`Returns: 6087`

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=3049

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=9900&pm=3049