#include <bits/stdc++.h>
#define pb push_back
#define mp make_pair
#define fr first
#define sc second
#define clr(a) memset(a, 0, sizeof(a))
#define sz(x) x.size()
#define printarray(arr) for (auto it = arr.begin(); it != arr.end(); ++it) cout<<*it<<" "; cout<<endl;
#define rep(n) for (ll i = 0; i < n; i++)
#define repc(i, n) for (ll i = 0; i < n; i++)
#define FOR(i, x, y) for (int i = x; i < y; i++)
#define DEC(i, x, y) for (int i = x; i >= y; i--)
#define all(v) v.begin(), v.end()
#define min3(a, b, c) min(a, min(b, c))
#define max3(a, b, c) max(a, max(b, c))
#define alla(a, n) a, a + n
#define gcd(a, b) __gcd(a, b)
#define lcm(a, b) (a * b)/gcd(a, b)
#define int long long int
#define ull unsigned long long
using namespace std;
const int MOD = 1e9 + 7;
const int MAXN = 1e5 + 5;
int fastexpo(int b, int exp){
if(exp == 0) return 1;
if(exp == 1) return b;
int ans = (fastexpo(b,exp/2) % MOD);
ans *= ans;
ans %= MOD;
if(exp % 2 == 1){
ans *= b;
}
ans %= MOD;
return ans;
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, k;
cin>>n>>k;
vector<int> vec;
for(int i= 0;i<n;i++){
int x; cin>>x;
vec.pb(x);
}
sort(all(vec));
vector<int> diff;
for(int i= 1;i<n;i++){
diff.pb((vec[i]-vec[i-1])-1);
}
sort(all(diff));
int tochoose = n-k;
int ans = 0;
for(int i= 0;i<tochoose;i++){
ans += diff[i];
}
ans += n;
cout<<ans<<endl;
return 0;
}
