// Author: ChungNotTrung;
// Created: 2024-12-02 14:33:08
// Problem: None
// Tag: None
// Source: None
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "C:\DEBUG\debugtemplate.cpp"
#else
#define debug(...)
#endif
#define ll long long
#define db long double
#define int long long
#define fi first
#define se second
#define pb push_back
#define ii pair<int, int>
#define vi vector<int>
#define vii vector<ii>
#define vvi vector<vi>
#define vvvi vector<vvi>
#define All(x) x.begin(), x.end()
#define file(name) fopen(name ".inp", "r") ? freopen(name ".inp", "r", stdin), freopen(name ".out", "w", stdout) : 0
#define file_trau(name) fopen(name ".inp", "r") ? freopen(name ".inp", "r", stdin), freopen(name ".ans", "w", stdout) : 0
#define Faster ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0)
#define Run_time cerr << " Time : " << (1.0 * clock() / CLOCKS_PER_SEC) << " s.\n"
#define bit(i, n) (1ll && ((1ll << i) & (n)))
#define ONBIT(i, mask) ((1ll << i) | (mask))
#define OFFBIT(i, mask) ((~(1ll << i)) & (mask))
#define MASK(n) (1ll << (n))
#define cnt_bit(n) (__builtin_popcountll(n))
#define Lg2(n) (63 - __builtin_clzll(n))
#define rep(i, x, n) for (int i = x; i <= n; ++i)
#define repd(i, n, x) for (int i = n; i >= x; --i)
#define REP(i, n) for (int i = 0; i < (int)(n); ++i)
#define repv(i, n) for (auto &i : n)
#define as_vi(v, n, val) v.assign(n + 1, val)
#define as_vvi(v, n, m, val) v.assign(n + 1, vi(m + 1, val))
#define as_vvvi(v, n, m, k, val) v.assign(n + 1, vvi(m + 1, vi(k + 1, val)))
#define left(id) (id << 1ll)
#define right(id) (id << 1ll | 1)
mt19937 rd(chrono::steady_clock().now().time_since_epoch().count());
int rng(int l, int r) { return uniform_int_distribution<int>(l, r)(rd); }
vi dx{0, 0, 1, -1, 1, 1, -1, -1};
vi dy{1, -1, 0, 0, -1, 1, -1, 1};
template <int D, typename T>
struct Vec : public vector<Vec<D - 1, T>>
{
static_assert(D >= 1, "Vector dimension must be greater than zero!");
template <typename... Args>
Vec(int n = 0, Args... args) : vector<Vec<D - 1, T>>(n, Vec<D - 1, T>(args...))
{
}
};
template <typename T>
struct Vec<1, T> : public vector<T>
{
Vec(int n = 0, const T &val = T()) : vector<T>(n, val)
{
}
};
template <class X, class Y>
bool maximize(X &a, const Y &b)
{
if (a < b)
return a = b, true;
return false;
}
template <class X, class Y>
bool minimize(X &a, const Y &b)
{
if (a > b)
return a = b, true;
return false;
}
const int base = 311;
const int nmax = 1e6 + 10;
const int oo = 1e18 + 100;
const int MOD = 1e9 + 7;
int sqr(int x)
{
return x * x;
}
int POW(int a, int n)
{
int res = 1;
while (n > 0)
{
if (n % 2 == 1)
res = (res * a) % MOD;
a = (a * a) % MOD;
n /= 2;
}
return res;
}
void fixmod(int &val)
{
if (val < 0)
val = (val + MOD * MOD) % MOD;
if (val >= MOD)
val %= MOD;
}
int ntest;
int n, k;
int a[nmax];
namespace sub2
{
int f[5005][5005];
void solve()
{
rep(i, 1, n)
{
f[1][i] = a[i] - a[1] + 1;
}
rep(c, 2, k)
{
rep(i, 1, n)
{
f[c][i] = oo;
repd(j, i - 1, 1)
{
minimize(f[c][i], f[c - 1][j] + a[i] - a[j + 1] + 1);
}
}
}
cout << f[k][n];
}
}
namespace full
{
void solve()
{
priority_queue<int> pq;
int sum = 0;
rep(i, 1, n - 1)
{
pq.push(a[i + 1] - a[i] - 1);
}
sum = a[n] - a[1] + 1;
rep(i, 2, k)
{
int x = pq.top();
pq.pop();
sum -= x;
}
cout << sum;
}
};
void TryHard()
{
cin >> n >> k;
rep(i, 1, n)
{
cin >> a[i];
}
sort(a + 1, a + 1 + n);
// sub2::solve();
full::solve();
}
main()
{
// Learning is like rowing upstream, not to advance is to drop back .
// A winner never stops trying .
Faster;
file("JOI18_stove");
// file_trau("");
ntest = 1;
// cin >> ntest;
while (ntest--)
{
TryHard();
cout << "\n";
}
}
// LIMIT :
/* /\_/\
( ._. )
/ >C< \
*/
