# Unique String Frequencies

Given a lowercase alphabet string `s`

, return the minimum number of characters that we need to delete such that the frequency of each character occurs a unique number of times.

**Constraints**

`n ≤ 100,000`

where`n`

is the length of`s`

https://binarysearch.com/problems/Unique-String-Frequencies

## Examples

### Example 1

**Input**

- s =
`aabb`

**Output**

- answer =
`1`

**Explanation**

Both `"a"`

and `"b"`

occur twice, so we can remove say `"a"`

once to make the frequencies unique.

### Example 2

**Input**

- s =
`abbccc`

**Output**

- answer =
`0`

**Explanation**

The string already has unique frequencies for `"a"`

, `"b"`

and `"c"`

: `[1, 2, 3]`

.

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