#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ld,ld> pld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pii> vpi;
typedef vector<pll> vpl;
#define pb push_back
#define popb pop_back
#define pf push_front
#define popf pop_front
#define all(x) (x).begin(),(x).end()
#define ff first
#define ss second
int nx[4] = {0,0,1,-1}, ny[4] = {1,-1,0,0};
ll gcd(ll a , ll b) {return b ? gcd(b , a % b) : a ;}
ll lcm(ll a , ll b) {return (a * b) / gcd(a , b);}
int n, k;
vll A;
void solve()
{
cin >> n >> k;
A.assign(n,0);
for(int i = 0; i < n ; i ++)
cin >> A[i];
sort(all(A));
vll B;
for(int i = 0; i < n - 1; i ++)
B.pb(A[i+1] - A[i]);
sort(all(B));
ll ans = n;
for(int i = 1; i <= n - k; i ++)
ans += B[i-1]-1;
cout << ans ;
}
int main()
{
ios::sync_with_stdio(false);
int tt = 1;
while(tt--)
solve();
}
