#include <bits/stdc++.h>
#define int long long
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
using namespace std;
signed main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n,k; cin >> n >> k;
vector<int> a(n);
vector<int> d(n-1);
for (int i = 0; i < n; i++) cin >> a[i];
sort(all(a));
int sum=a[n-1]-a[0]+1;
for (int i = 0; i < n-1; i++) {
d[i]=a[i+1]-a[i];
}
sort(rall(d));
for (int i = 0; i < min(sz(d),k-1); i++)
{
sum-=d[i]-1;
}
cout << sum << "\n";
return 0;
}
