#include <iostream>
#include <vector>
#include <algorithm>
#include <set>
#include <climits>
#include <stack>
#include <map>
#include <unordered_set>
#include <cmath>
#include <iomanip>
#include <queue>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")
using namespace std;
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
#define all(a) begin(a), end(a)
#define pb push_back
#define nl '\n'
#define sz(x) (int)x.size()
#define in insert
#define speed ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define ppb pop_back
#define ld long double
const int N = 2e5 + 10;
const int mod = 998244353;
int gcd(int a, int b) {
if(!b) return a;
return gcd(b, a % b);
}
const int C = 1e9 + 10;
const int INF = LLONG_MAX;
void solve() {
int n, k;
cin >> n >> k;
vector<int> a(n), v;
for(int i = 0; i < n; i++) cin >> a[i];
sort(all(a));
for(int i = 1; i < n; i++) v.pb(a[i] - a[i-1] - 1);
sort(all(v));
int ans = a.back() - a[0] + 1;
k--;
for(int i = sz(v)-1; i > -1 && k; i--, k--) {
ans -= v[i];
}
cout << ans << nl;
}
signed main() {
speed;
int T = 1;
//cin >> T;
for(int _ = 0; _ < T; _++)
solve();
}
/*
4
amir rima amin nim
*/
