#include <bits/stdc++.h>
#define int long long
#define ssize(x) (int)x.size()
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
const int N = 1E5 + 5;
int n, k;
int t[N];
void solve() {
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> t[i];
}
sort(t + 1, t + 1 + n);
vector<int> diff;
for (int i = 1; i + 1 <= n; i++) {
diff.push_back(t[i + 1] - t[i]);
}
sort(diff.begin(), diff.end());
int ans = 0;
for (int i = 0; i < n - k; i++) {
ans += diff[i];
}
cout << ans + k << '\n';
}
signed main() {
cin.tie(0) -> sync_with_stdio(0);
int tc = 1;
// cin >> tc;
while (tc--) solve();
return 0;
}
