#include <bits/stdc++.h>

using namespace std;

#define fst(t) std::get<0>(t)
#define snd(t) std::get<1>(t)
#define thd(t) std::get<2>(t)
#define unless(p) if(!(p))
#define until(p) while(!(p))

using ll = long long;
using P = std::tuple<int,int>;

const int dx[8] = {-1, 1, 0, 0, -1, -1, 1, 1}, dy[8] = {0, 0, -1, 1, -1, 1, -1, 1};

int N, K;
ll A[50010];
priority_queue<ll, vector<ll>, greater<ll> > pq;

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

    std::cin >> N >> K;

    for(int i=0;i<N;++i){
        std::cin >> A[i];
    }

    sort(A, A+N);
    
    for(int i=0;i+1<N;++i){
        pq.emplace(- A[i + 1] + A[i]);
    }

    ll res = A[N-1] - A[0];
    for(int i=0;i<K-1;++i){
        ll x = pq.top();
        pq.pop();

        res += x;
    }

    std::cout << res << std::endl;
}