// No.615 集合に分けよう
// https://yukicoder.me/problems/no/615
//

#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
using namespace std;

long long int solve(unsigned int N, unsigned int K, vector<long long int> &numbers);


int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    unsigned int N, K;
    cin >> N >> K;
    vector<long long> numbers(N);
    for (int i = 0; i < N; ++i)
        cin >> numbers[i];
    long long ans = solve(N, K, numbers);
    cout << ans << endl;
}

long long int solve(unsigned int N, unsigned int K, vector<long long int> &numbers) {
    sort(numbers.begin(), numbers.end());
    vector<pair<long long, int>> gaps;
    for (int i = 1; i < N; ++i)
        gaps.push_back(make_pair(-(numbers[i] - numbers[i-1]), i));
    
    sort(gaps.begin(), gaps.end());
    
    long long ans = 0;
    int b = 0;
    for (int i = 0; i+1 < K; ++i) {
        int pos = gaps[i].second;
        ans += (numbers[pos-1] - numbers[b]);
        b = pos;
    }
    ans += numbers[N-1] - numbers[b];
    return ans;
}