#include <bits/stdc++.h>

using namespace std;

#define LL long long
const int N = 1e6 + 10;

LL a[100000], b[100000];
int main()
{	
	LL n, k;
	cin >> n >> k;
	for(LL i = 1; i <= n; i++)
	{
		cin >> a[i];
	}
	sort(a + 1, a + n + 1);
	LL s = 0, sum = 0;
	for(LL i = 1; i <= n; i++)
	{
		b[++sum] = a[i] - a[i - 1];
	}
	sort(b + 1, b + sum + 1);
	for(int i = 1; i <= n / 2; i++)
	{
		s += b[i];
	}
	cout << s;
	return 0;
}

为啥爆零了