/*
ID: agageld1
LANG: C++17
TASK:
*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define N 400005
#define ff first
#define ss second
#define pb push_back
#define sz(s) (int)s.size()
ll n, t, ans, a[N], s;
map <int,int> vis;
vector<pair<int,pair<int,int>>> v;
int main () {
ios::sync_with_stdio(0);cin.tie(0);
cin >> n >> t;
s = n;
ans = n;
for(int i = 1; i <= n; i++) {
cin >> a[i];
}
sort(a+1,a+n+1);
for(int i = 1; i < n; i++) {
v.pb({a[i+1] - a[i],{i,i+1}});
}
sort(v.begin(),v.end());
for(auto i:v) {
if(s == t) break;
s--;
ans += i.ff+1;
ans -= 2;
}
cout << ans << '\n';
}
