#include <cassert>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <iomanip>
#include <limits.h>
#include <map>
#include <queue>
#include <set>
#include <string.h>
#include <vector>

using namespace std;
typedef long long ll;

const ll MOD = 1000000007;

struct Node {
  int idx;
  ll diff;

  Node(int idx = -1, ll diff = -1) {
    this->idx = idx;
    this->diff = diff;
  }

  bool operator>(const Node &n) const {
    return diff < n.diff;
  }
};

int main() {
  int N, K;
  cin >> N >> K;
  vector<ll> A;
  ll a;

  for (int i = 0; i < N; ++i) {
    cin >> a;
    A.push_back(a);
  }

  sort(A.begin(), A.end());

  priority_queue <Node, vector<Node>, greater<Node>> pque;

  for (int i = 0; i + 1 < N; ++i) {
    ll a = A[i];
    ll b = A[i + 1];

    pque.push(Node(i, b - a));
  }

  bool dividePoint[N];
  memset(dividePoint, false, sizeof(dividePoint));

  for (int i = 0; i < K - 1; ++i) {
    Node node = pque.top();
    pque.pop();

    // fprintf(stderr, "%d - %d: %lld\n", node.idx, node.idx + 1, node.diff);
    dividePoint[node.idx] = true;
  }

  ll ans = 0;
  int s = 0;

  for (int i = 0; i < N; ++i) {
    if (!dividePoint[i]) continue;

    // fprintf(stderr, "%d -> %d\n", s, i);
    ans += A[i] - A[s];
    s = i + 1;
  }

  ans += A[N - 1] - A[s];

  cout << ans << endl;

  return 0;
}