#include<bits//stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < n;i++)
int main() {
	int t, n,p;priority_queue<int> pq;
	cin >> n >> t;vector<int> x(t);
	if (n >= t) {
		cout << 0 ;
		return 0;
	}
	rep(i, t) cin >> x[i];
	sort(x.begin(), x.end());
	rep(i, t - 1) pq.push(x[i + 1] - x[i]);
	p = x[t - 1] - x[0];
	rep(i, n - 1) {
		p -= pq.top();pq.pop();
	}
	cout << p ;
}
### Prompt

Develop a solution in Cpp to the problem described below:

We will play a one-player game using a number line and N pieces.

First, we place each of these pieces at some integer coordinate.

Here, multiple pieces can be placed at the same coordinate.

Our objective is to visit all of the M coordinates X_1, X_2, ..., X_M with these pieces, by repeating the following move:

Move: Choose a piece and let x be its coordinate. Put that piece at coordinate x+1 or x-1.

Note that the coordinates where we initially place the pieces are already regarded as visited.

Find the minimum number of moves required to achieve the objective.

Constraints

* All values in input are integers.
* 1 \leq N \leq 10^5
* 1 \leq M \leq 10^5
* -10^5 \leq X_i \leq 10^5
* X_1, X_2, ..., X_M are all different.

Input

Input is given from Standard Input in the following format:


N M
X_1 X_2 ... X_M


Output

Find the minimum number of moves required to achieve the objective.

Examples

Input

2 5
10 12 1 2 14


Output

5


Input

3 7
-10 -3 0 9 -100 2 17


Output

19


Input

100 1
-100000


Output

0

### Response

```cpp
#include<bits//stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < n;i++)
int main() {
	int t, n,p;priority_queue<int> pq;
	cin >> n >> t;vector<int> x(t);
	if (n >= t) {
		cout << 0 ;
		return 0;
	}
	rep(i, t) cin >> x[i];
	sort(x.begin(), x.end());
	rep(i, t - 1) pq.push(x[i + 1] - x[i]);
	p = x[t - 1] - x[0];
	rep(i, n - 1) {
		p -= pq.top();pq.pop();
	}
	cout << p ;
}
```