#include <bits/stdc++.h>
using namespace std;
class Heap {
struct HeapNode {
int val;
vector <HeapNode*> fii;
HeapNode(int val) : val(val) { }
} *root;
HeapNode* join(HeapNode* a, HeapNode* b) {
if (a == 0)
return b;
if (b == 0)
return a;
if (a->val < b->val) {
a->fii.push_back(b);
return a;
}
// else
b->fii.push_back(a);
return b;
}
public:
Heap() : root(0) { }
void push(int val) {
HeapNode* nod = new HeapNode(val);
root = join(root, nod);
}
int top() {
assert(root != 0);
return root->val;
}
void pop() {
HeapNode* new_root = 0;
if (root->fii.size() % 2 == 1)
root->fii.push_back(0);
for (int i = 0; i < (int)root->fii.size(); i += 2)
new_root = join(new_root,
join(root->fii[i], root->fii[i + 1]));
delete root;
root = new_root;
}
};
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, k;
cin >> n >> k;
vector <int> v(n);
for (auto& i : v)
cin >> i;
sort(v.begin(), v.end());
int interv_need = max(0, (int)v.size() - k);
Heap pq;
for (int i = 1; i < (int)v.size(); i++)
pq.push(v[i] - v[i - 1] - 1);
int ans = v.size();
for (int _ = 0; _ < interv_need; _++) {
ans += pq.top();
pq.pop();
}
cout << ans << '\n';
return 0;
}
