#include <bits/stdc++.h>
#define pb push_back
using namespace std;
#define F first
#define sz size()
#define S second
#define in insert
#define lb lower_bound
#define int long long
#define all(v) v.begin(), v.end()
#define FOR(x, n, m, d) for(int x = n; x <= m; x += d)
#define FORR(x, n, m, d) for(int x = n; x >= m; x -= d)
#define nikita ios_base::sync_with_stdio(0), cin.tie(0);
const int N = 1e6+5;
int n,m,tt,sum=0,l, r, x, y, cnt, block = 448, res, k;
int a[N], b[N], c[N], ans, pref[N], mod =998244353, suf[N], d[N];
string s;
void solve() {
cin >> n >> m;
FOR(i,1,n,1)cin>>a[i];
sort(a+1, a+n+1);
ans = n;
if(m >= n){
cout<<ans;
return;
}
multiset<int>st;
FOR(i, 2, n, 1){
st.in(a[i]-a[i-1]-1);
}
k = n - m;
FOR(i, 1, k, 1){
ans += *st.begin();
st.erase(st.find(*st.begin()));
}
cout<<ans;
}
signed main()
{
nikita
tt = 1;
if(!tt)cin >> tt;
FOR(i, 1, tt, 1){
solve();
}
}
