#pragma gcc optimize("Ofast")
#include <vector>
#pragma gcc target("avx, avx2, popcnt, lzcnt")
#include <bits/stdc++.h>
#include <experimental/random>
using namespace std;
void solve1();
using ll = long long;
using ull = unsigned long long;
using ld = double;
using BIG = __int128_t;
# define int long long
# define chmin(a, b) a = min(a, b)
const int MOD = 1e9 + 7;
const int INF = 1e18;
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int qwerty = 1;
// cin >> qwerty;
while (qwerty--) {
solve1();
}
}
void solve1() {
int n, k;
cin >> n >> k;
vector<int> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
sort(a.begin(), a.end());
vector<int> b;
for (int i = 1; i < n; i++) {
b.push_back({a[i] - a[i - 1] - 1});
}
sort(b.rbegin(), b.rend());
int all = a[n - 1] - a[0] + 1;
for (int i = 0; i < min((int) b.size(), k - 1); i++) {
all -= b[i];
}
cout << all;
}
