#pragma GCC optimize ("-O3","unroll-loops")
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<math.h>
#include<iomanip>
#include<set>
#include<numeric>
#include<cstring>
#include<cstdio>
#include<functional>
#include<bitset>
#include<limits.h>
#include<cassert>
#include<iterator>
#include<complex>
#include<stack>


#define REP(i, n) for(int i = 0;i < n;i++)
#define REPR(i, n) for(int i = n;i >= 0;i--)
#define FOR(i, m, n) for(int i = m;i < n;i++)
#define FORR(i, m, n) for(int i = m;i >= n;i--)
#define SORT(v, n) sort(v, v+n);
#define VSORT(v) sort(v.begin(), v.end());
#define REVERSE(v,n) reverse(v,v+n);
#define VREVERSE(v) reverse(v.begin(), v.end());
#define ll long long
#define pb(a) push_back(a)
#define m0(x) memset(x,0,sizeof(x))
#define print(x) cout<<x<<'\n';
#define pe(x) cout<<x<<" ";
#define lb(v,n) lower_bound(v.begin(), v.end(), n);
#define ub(v,n) upper_bound(v.begin(), v.end(), n);
#define int long long
//#define int unsigned long long
#define all(x) (x).begin(), (x).end()
#define double long double

using namespace std;

template<class T> inline bool chmin(T& a, T b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}
template<class T> inline bool chmax(T& a, T b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}

int MOD = (ll)1000000000 + 7;
const ll INF = 1e17;
const double pi = acos(-1);
const double EPS = 1e-10;
typedef pair<int, int>P;
const int MAX = 200020;

vector<int>v,diff;
signed main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	int N, K; cin >> N >> K;
	v.resize(N);
	REP(i, N) {
		cin >> v[i];
	}
	VSORT(v);
	ll ans = 0;
	REP(i, N - 1) {
		diff.pb(v[i + 1] - v[i]);
		ans += diff[i];
	}
	VSORT(diff);
	VREVERSE(diff);
	REP(i, K - 1) {
		ans -= diff[i];
	}
	print(ans);
}