#include "bits/stdc++.h"
using namespace std;
using ll = long long;
void solve() {
int n, k;
cin >> n >> k;
vector<ll> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
sort(a.begin(), a.end());
ll ans = a[n - 1] - a[0] + 1;
k--;
int l = 0;
vector<ll> t;
while (l < n) {
while (l < n - 1 && a[l] + 1 == a[l + 1]) {
l++;
}
if (l < n - 1) {
t.push_back(a[l + 1] - a[l] - 1);
}
l++;
}
sort(t.rbegin(), t.rend());
for (int i = 0; i < min(k, (int)t.size()); i++) {
ans -= t[i];
}
cout << ans << '\n';
}
int main() {
ios::sync_with_stdio(false);
cin.tie(0);
int test = 1;
// cin >> test;
while (test--) {
solve();
}
}
