Letters and Scales

Interview

Time limit2sMemory limit1024 MB

Summary

Given n scales and a word s, find the minimum number of cubes needed to show s on the scales in a row, or report Impossible.

Level: Easy1 of 10
Topics: Implementation
Solved: No attempts yet

Problem

Little Petya received an unusual New Year present: a set of scales and cubes. These scales do not show weight. Instead, they show letters. An empty scale shows nothing, one cube shows $a$ , two cubes show $b$ , and 26 cubes show $z$ . If more than 26 cubes are put on a scale, it breaks.

Petya played with the cubes and scales for a long time. He broke some scales and lost some cubes. He now has $n$ scales in total. Petya wants the scales, placed in a row, to show the word $s$ , but he does not know whether that is possible. Help him. Write a program that, given $n$ and the word $s$ , finds the minimum number of cubes needed to show $s$ , or reports that it is impossible.

Input

The first line contains one integer $n$ ( $1 \le n \le 100$ ). The second line contains the word $s$ , consisting of lowercase Latin letters. The length of $s$ does not exceed 100.

Output

If the word cannot be written, print the single word Impossible. Otherwise, print one integer: the minimum number of cubes needed to write $s$ with the scales and cubes.

Examples2

Example 1
Input
```
20
impossible
```
Expected output
```
119
```
Example 2
Input
```
5
impossible
```
Expected output
```
Impossible
```