## LCC/Moose '19 Contest 2 J2 - Characteristic Characters

Derek really likes string manipulations, but he is having trouble finding the index of a certain character in his string.

He wants to find the \(N_{th}\) occurrence of the \(K_{th}\) character.

Output the index of that character.

#### Input Specification

The first line will contain the two integers, \(N\) \((1 \le N\le 10^5)\) and \(K\) \((0 \le K\le 10^5-1)\).

The second line will contain a string of length \(\le10^5\) lowercase, latin characters.

It is guaranteed that the \(K_{th}\) character will appear at **least** \(N\) times.

#### Output Specification

On the first line, output the **zero-based** index of the \(N_{th}\) occurrence of the \(K_{th}\) character in the string.

#### Sample Input 1

```
1 2
abca
```

#### Sample Output 1

`2`

#### Sample Input 2

```
5 1
ababbbbbbbbbb
```

#### Sample Output 2

`6`

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