#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define endl "\n"
#define pq priority_queue
using namespace std;
const ll MAXN = 100005;
ll n, k;
vector<pair<ll, ll>> pa;
vector<pair<ll, ll>> nw;
vector<pair<ll, ll>> inter() {
nw.clear();
nw.push_back(pa[0]);
for (int i = 1; i < n; i++) {
ll st = pa[i].fi;
ll ed = pa[i].se;
ll& led = nw.back().se;
if (st <= led) {
led = max(led, ed);
} else {
nw.push_back({st, ed});
}
}
return nw;
}
int main() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
ll x;
cin >> x;
pa.push_back({x, x + 1});
}
sort(pa.begin(), pa.end());
inter();
ll m = nw.size();
ll tong = 0;
for (auto x : nw) {
tong += x.se - x.fi;
}
if (m <= k) {
cout << tong;
return 0;
}
vector<ll> gap;
for (int i = 1; i < m; i++) {
gap.push_back(nw[i].fi - nw[i - 1].se);
}
sort(gap.begin(), gap.end());
for (int i = 0; i < m - k; i++) {
tong += gap[i];
}
cout << tong;
return 0;
}
