### Problem Statement

There are some chickens and some cows in Farmer John's yard.

John's daughter Susie counted that all the animals in the yard have a total of 3 heads. John's son Billy counted their legs and got a total of 8. Using their answers, Farmer John easily determined that there have to be exactly 2 chickens and 1 cow.

Write a method that will solve a general version of Farmer John's problem. You are given two ints heads and legs. Compute the number of chickens and the number of cows. Return a int[] with two elements: first the number of chickens, then the number of cows. If there is no solution, return an empty int[] instead.

### Definition

 Class: OnTheFarmDivTwo Method: animals Parameters: int, int Returns: int[] Method signature: int[] animals(int heads, int legs) (be sure your method is public)

### Notes

-If the solution exists, it is always unique.
-A chicken has 1 head and 2 legs. A cow has 1 head and 4 legs.

### Constraints

-heads will be between 0 and 1,000,000, inclusive.
-legs will be between 0 and 1,000,000, inclusive.

### Examples

0)

 `3` `8`
`Returns: {2, 1 }`
 Two chickens and a cow have a total of three heads and eight legs.
1)

 `10` `40`
`Returns: {0, 10 }`
 Ten cows.
2)

 `10` `42`
`Returns: { }`
 This test case has no solution because the number of legs is too large (or the number of heads is too small).
3)

 `1` `3`
`Returns: { }`
 No set of animals can have one head and three legs.
4)

 `0` `0`
`Returns: {0, 0 }`

#### Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=10974

#### Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=14155&pm=10974

misof

#### Testers:

PabloGilberto , bmerry , ivan_metelsky

#### Problem categories:

Brute Force, Simple Math