#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long long a[50050];
int main() {
    long long n, k;
    cin >> n >> k;
    k = n - k;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);
    vector<long long> vec;
    for (int i = 1; i < n; i++) {
        vec.emplace_back(a[i] - a[i - 1]);
    }
    sort(vec.begin(), vec.end());
    long long ans = 0;
    for (int i = 0; i < k; i++) {
        ans += vec[i];
    }
    cout << ans << endl;
}