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###### Description

An array `arr`

is given. Each element of `arr`

is a number between 0 through 9. You want to remove all the duplicate numbers in the array `arr`

except for only one. However, the order of each element in the array `arr`

should be maintained. For example,

- When arr = [1, 1, 3, 3, 0, 1, 1], return [1, 3, 0, 1].
- When arr = [4, 4, 4, 3, 3], return [4, 3].

Write a function solution to return the remaining numbers after removing the duplicate numbers in the array `arr`

except only one.

##### Constraints

- Length of array
`arr`

: natural number less than or equal to 1,000,000. - Element of array
`arr`

: integer between 0 and 9.

##### Examples

arr | answer |
---|---|

[1,1,3,3,0,1,1] | [1,3,0,1] |

[4,4,4,3,3] | [4,3] |

Example #1,2

It is the same as the example in the problem statement.

Result
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