##### DWITE Online Computer Programming Contest, October 2007, Problem 4

Some kids play with blocks, and build things by stacking different blocks on top of each other. Given a set of blocks and a target height, we want to find out if it's possible to construct a stack with an exact specified height.

The input will contain at least lines, one positive integer value per line. The first line will contain an integer , the target height for the stack.

The second line will contain an integer , number of blocks in a set.

The next lines will contain integers, one per line; ; representing the height of blocks in the set.

The output file will contain a single integer value, a minimum number of blocks out of the supplied set, required to build a stack of the given height. If it is impossible to build the desired stack, output .

#### Sample Input 1

```
5
3
1
2
3
```

#### Sample Output 1

`2`

#### Sample Input 2

```
10
3
1
5
7
```

#### Sample Output 2

`0`

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