#include <bits/stdc++.h>

using namespace std;

const int MAX = 5e4 + 10;
int N, K;
long long a[MAX];

int main() {
    scanf("%d%d", &N, &K);
    for (int i = 0; i < N; i++) {
        scanf("%lld", a + i);
    }
    sort(a, a + N);
    priority_queue<pair<long long, int>> pq;
    for (int i = 0; i < N - 1; i++) {
        pq.emplace(a[i + 1] - a[i], i);
    }
    vector<int> splitIdx;
    for (int i = 0; i < K - 1; i++) {
        splitIdx.emplace_back(pq.top().second);
        pq.pop();
    }
    splitIdx.emplace_back(N - 1);
    long long ans = 0;
    int ptr = 0;
    for (int e : splitIdx) {
        //cerr << e << endl;
        ans += a[e] - a[ptr];
        ptr = e + 1;
    }
    cout << ans << endl;
    return 0;
}