The alphabetical sum of an alphabetic string is defined as the sum of the indices of each character in the alphabet. For example, the alphabetical value of the string `abce`

is , since the indices of `a`

, `b`

, `c`

, and `e`

are , , , and , respectively, and .

Steven has a string which consists strictly of lowercase letters and asterisks. The asterisks can each be replaced with any lowercase letter in the English alphabet.

Given an integer , representing Tommy's desired alphabetical sum, Steven wonders whether it is possible to construct a string with an alphabetical sum of by replacing the asterisks in his string. If it is, he wants to know the lexicographically smallest such string.

Definition: A string is lexicographically smaller than a string if and at the first index where , .

#### Input Specification

The input consists of two lines. The first line contains , representing Tommy's desired alphabetical sum. The second line contains , representing the string Steven has.

The following table shows how the available 15 marks are distributed.

Mark Awarded | Expected Alphabetical Value | Length of Steven's String |
---|---|---|

marks | ||

marks |

#### Output Specification

If it is impossible to construct a string that satisfies Tommy's expectations, output `Impossible`

.

Otherwise, output the lexicographically smallest string such that the alphabetical sum of the string is .

#### Sample Input 1

```
2
a*
```

#### Output for Sample Input 1

`aa`

#### Explanation of Output for Sample Input 1

The alphabetical sum of `aa`

is . It can be shown that `aa`

is the only possible string in this case.

#### Sample Input 2

```
4
a**
```

#### Output for Sample Input 2

`aab`

#### Explanation of Output for Sample Input 2

The alphabetical value of `aab`

is . Other possible strings like `aba`

also have as the alphabetical sum, but `aab`

is the lexicographically smallest.

#### Sample Input 3

```
1
a*
```

#### Output for Sample Input 3

`Impossible`

#### Explanation of Output for Sample Input 3

It can be shown that we cannot construct a string for this case that has an alphabetical sum of .

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