#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ull = unsigned long long;
#define all(x) x.begin(), x.end()
template <typename T1, typename T2> inline void chkmin(T1 &x, const T2 & y) {if (x > y) x = y;}
template <typename T1, typename T2> inline void chkmax(T1 &x, const T2 & y) {if (x < y) x = y;}
int n, k;
vector<int> a;
void read() {
cin >> n >> k;
a.resize(n);
for (auto &i : a)
cin >> i;
sort(all(a));
}
ll ans;
void run() {
vector<int> d;
for (int i = 0; i + 1 < n; i++) {
d.push_back(a[i + 1] - a[i]);
}
sort(all(d));
ans = k;
k--;
while (k && !d.empty()) {
d.pop_back();
k--;
}
for (auto i : d) {
ans += i;
}
}
void write() {
cout << ans << endl;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
read();
run();
write();
return 0;
}
