#include <bits/stdc++.h>
using namespace std;
#define scd(t) scanf("%d", &t)
#define scld(t) scanf("%ld", &t)
#define sclld(t) scanf("%lld", &t)
#define scc(t) scanf("%c", &t)
#define scs(t) scanf("%s", t)
#define scf(t) scanf("%f", &t)
#define sclf(t) scanf("%lf", &t)
#define forr(i, j, k) for (int i = j; i < k; i++)
#define frange(i, j) forr(i, 0, j)
#define all(cont) cont.begin(), cont.end()
#define mp make_pair
#define pb push_back
#define f first
#define s second
typedef long int li;
typedef unsigned long int uli;
typedef long long int lli;
typedef unsigned long long int ulli;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<lli> vll;
typedef vector<string> vs;
typedef vector<pii> vii;
typedef vector<vi> vvi;
typedef map<int, int> mpii;
typedef set<int> seti;
typedef multiset<int> mseti;
typedef long double ld;
void fastio()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
}
int main()
{
fastio();
int n, k;
cin >> n >> k;
vector<pair<lli, lli>> vec(n);
lli tot = 0;
frange(i, n)
{
cin >> vec[i].f;
vec[i].s = vec[i].f + 1;
tot += vec[i].s - vec[i].f;
}
sort(all(vec));
vll diff(n - 1);
frange(i, n - 1)
{
diff[i] = vec[i + 1].f - vec[i].s;
}
sort(all(diff));
frange(i, n - k)
{
tot += diff[i];
}
cout << tot;
}
