#include <bits/stdc++.h>
// mrrrowwww meeowwwww :3
// go play vivid/stasis! !! !!! https://vividstasis.gay
#define fo(i, a, b) for (auto i = (a); i < (b); i++)
#define of(i, a, b) for (auto i = (b); i-- > (a);)
#define f first
#define s second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define be(a) a.begin(), a.end()
using namespace std;
int ____init = []{
ios::sync_with_stdio(false);
cin.tie(NULL); cout.tie(NULL);
return 0;
}();
int t[100000];
bool off[100000];
pair<int, int> edges[99999];
int main() {
int n, k; cin >> n >> k;
fo(i, 0, n) cin >> t[i];
fo(i, 1, n) off[i - 1] = true, edges[i - 1] = { t[i] - t[i - 1], i - 1 }; off[n - 1] = true;
sort(edges, edges + n - 1);
fo(i, 0, n - k) off[edges[i].s] = false;
int res = 0;
for (int i = 0, j = 0; i < n; i++)
if (off[i]) res += t[i] + 1 - t[j], j = i + 1;
cout << res;
}
