#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k;
cin >> n >> k;
vector<ll> A(n);
for(int i = 0; i < n; i++){
cin >> A[i];
}
if(k >= n){
// You can put each element in its own segment
cout << n << "\n";
return 0;
}
sort(A.begin(), A.end());
// Compute the n-1 gaps between consecutive points:
vector<ll> gaps;
gaps.reserve(n-1);
for(int i = 1; i < n; i++){
gaps.push_back(A[i] - A[i-1]);
}
// Sort gaps descending:
sort(gaps.begin(), gaps.end(), greater<ll>());
// Base cost is covering everything in one segment:
ll cost = (A[n-1] - A[0] + 1);
// Subtract the (k-1) largest (gap - 1) savings:
for(int i = 0; i < k-1; i++){
cost -= (gaps[i] - 1);
}
cout << cost << "\n";
return 0;
}
