#include <bits/stdc++.h>
#define ll long long
#define fi first
#define se second
#define sz(x) (int)x.size()
#define ALL(v) v.begin(),v.end()
#define MASK(k) (1LL << (k))
#define BIT(x, i) (((x) >> (i)) & 1)
#define oo (ll)1e18
#define INF (ll)1e9
#define MOD (ll)(1e9 + 7)
using namespace std;
template<class T1, class T2>
bool maximize(T1 &a, T2 b){if(a < b){a = b; return true;} return false;}
template<class T1, class T2>
bool minimize(T1 &a, T2 b){if(a > b){a = b; return true;} return false;}
template<class T1, class T2>
void add(T1 &a, T2 b){a += b; if(a >= MOD) a -= MOD;}
template<class T1, class T2>
void sub(T1 &a, T2 b){a -= b; if(a < 0) a += MOD;}
template<class T>
void cps(T &v){sort(ALL(v)); v.resize(unique(ALL(v)) - v.begin());}
void solve(){
int n, k; cin >> n >> k;
minimize(k, n);
vector<int> T(n);
for(int i = 0; i < n; i++) cin >> T[i];
sort(ALL(T));
vector<int> ord;
for(int i = 1; i < n; i++) ord.push_back(T[i] - T[i - 1]);
sort(ALL(ord), greater<int>());
int cur = 0;
for(int i = 0; i + 1 < k; i++){
cur += ord[i];
}
cout << T[n - 1] - T[0] + k - cur << '\n';
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
// freopen("durian.inp","r",stdin);
// freopen("durian.out","w",stdout);
solve();
return 0;
}
