# Base 3 to Integer

Given a string `s`

representing a number in base 3 (consisting only of 0, 1, or 2), return its decimal integer equivalent. This should be implemented directly without using a built-in function.

https://binarysearch.com/problems/Base-3-to-Integer

## Examples

### Example 1

**Input**

- s =
`10`

**Output**

- answer =
`3`

### Example 2

**Input**

- s =
`21`

**Output**

- answer =
`7`

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