#include <bits/stdc++.h>
using namespace std;
#define ll long long int
#define rep(i, a, b) for(ll i = a; i < b; i++)
#define rep_(i, a, b) for(ll i = a; i > b; i--)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define vll vector<ll>
#define vvll vector<vll>
#define pll pair<ll, ll>
constexpr ll mod = 1e9+7, inf = LLONG_MAX, N = 2e5+23;
ll n, k;
ll t[N], p[N], sz[N];
pll a[N];
ll find(ll u){
if(u==p[u]) return u;
return p[u] = find(p[u]);
}
bool join(ll u, ll v){
u = find(u), v = find(v);
if(u==v) return false;
if(sz[u]<sz[v]) swap(u, v);
sz[u] += sz[v];
p[v] = u;
return true;
}
void solve(){
cin >> n >> k;
for(ll i = 0; i < n; ++i) p[i] = i;
for(ll i = 0; i < n; ++i) cin >> t[i];
for(ll i = 1; i < n; ++i) a[i-1] = {t[i]-t[i-1], i-1};
sort(a, a+(n-1));
ll cnt = n, res = k;
for(ll i = 0; i < n-1; ++i){
if(cnt==k) break;
// cout << a[i].first << " " << a[i].second;
bool cur = join(a[i].second, a[i].second+1);
res += a[i].first;
if(cur) --cnt;
}
cout << res;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
while(t--) solve();
return 0;
}
