#include <bits/stdc++.h>
using namespace std;
typedef int64_t ll;
typedef string str;
#define pb push_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
signed main() {
int n, k;
cin >> n >> k;
ll a[n], ans = 0;
for (int i = 0; i < n; i++) cin >> a[i];
if (n == 1) {
cout << 1;
return 0;
}
sort(a, a + n);
ans = a[n - 1] - a[0] + 1;
vector <ll> diff;
for (int i = 1; i < n; i++) {
diff.pb(a[i] - a[i - 1]);
}
k--;
sort(all(diff));
while (k && !diff.empty()) {
k--;
ans -= diff.back() - 1;
diff.ppb();
}
cout << ans;
}
