#include <bits/stdc++.h>
using namespace std;
#define kien long long
#define int long long
#define pb push_back
#define FOR(i, a, b) for (int i = a;i <= b; i++)
#define FORD(i, a, b) for (int i = a;i >= b; i--)
#define pii pair<int, int>
#define dembit(a) __builtin_popcountll(a)
#define task "kien"
#define fin(x) freopen(x".inp","r",stdin)
#define fou(x) freopen(x".out","w",stdout)
#define debug(x) cout << x << " "
#define down cout << "\n"
const kien MOD = 1e9 + 7;
const int NTEST = 100;
const int Million = 1e6;
const int MXN = 1e5 + 5;
const int INF = 1e15;
mt19937 rd(chrono::high_resolution_clock::now().time_since_epoch().count());
kien rand(kien l, kien r) {
assert(l <= r);
return uniform_int_distribution<kien>(l, r)(rd);
}
kien n, k, m, u, v, h, a[MXN], b[MXN];
kien maxx, minn, vtr, x, l, r, ans;
void solve() {
cin >> n >> k;
FOR (i, 1, n) cin >> a[i];
sort(a + 1, a + n + 1);
if (k >= n) {
cout << n;
return;
}
FOR (i, 1, n - 1) {
b[i] = a[i + 1] - a[i] - 1;
}
sort (b + 1, b + n);
ans = n;
FOR(i, 1, n - k) {
ans += b[i];
}
cout << ans;
}
main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
if (fopen(task".inp", "r")) {
fin(task); //fou(task);
}
int t = 1; //cin >> t;
while(t--) solve();
}
