#include <bits/stdc++.h>
#define sts(v) stable_sort(v.BE, v.E)
#define Rsts(v) stable_sort(v.rBE, v.rE)
#define rev(v) reverse(v.BE, v.E)
#define BE begin()
#define rBE rbegin()
#define E end()
#define rE rend()
#define pb push_back
#define ppb pop_back()
#define pf push_front
#define ppf pop_front()
#define F first
#define S second
using namespace std;
using ll = long long;
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
int n, k; cin >> n >> k;
vector<int> v(n);
for(int &i : v)cin >> i;
sts(v);
ll ans = n;
priority_queue<int> q;
k--;
for(int i = 1; i < n; i++)
q.push(v[i] - v[i - 1]);
while(k-- && q.size())
q.pop();
while(q.size()){
ans += q.top() - 1;
q.pop();
}
cout << ans << '\n';
return 0;
}
