##### 2017 Winter Waterloo Local ACM Contest, Problem B

Vera is learning about the longest common subsequence problem.

A string is a (possibly empty) sequence of lowercase letters. A subsequence of a string is a string obtained by deleting some letters of (possibly none or all). For example `vra`

, `a`

, ` (empty string), and `

`vera`

are all subsequences of `vera`

. The *longest common subsequence (LCS)* of two strings and is a string that is a subsequence of both and that has the maximum length among all strings that are a subsequence of both and . There could be multiple LCS for two given strings. For example, a LCS of `vera`

and `eats`

is `ea`

.

For homework, she was given two strings , , both of length and she had to determine the length of the LCS of and . She determined the answer to be but lost . Given and , help her find a possible value of . It is possible that Vera may have made a mistake and no such exists, in that case output `WRONGANSWER`

.

#### Constraints

- , are integers
- consists of lowercase letters

#### Input Specification

The input will be in the format:

#### Output Specification

Output one line consisting of the string of lowercase letters, or `WRONGANSWER`

if no is valid. If there are multiple correct output any of them.

#### Sample Input 1

```
4 2
vera
```

#### Sample Output 1

`eats`

#### Explanation of Sample Output 1

Another possible answer is `uber`

.

#### Sample Input 2

```
4 5
vera
```

#### Sample Output 2

`WRONGANSWER`

## Comments

Since the original data were weak, an additional test case was added, and all submissions were rejudged.