#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
#define ll long long
ll mod = 998244353;
//mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll binpow(ll a, ll b)
{
ll res = 1;
while (b>0)
{
if (b&1)
res = (res*a)%mod;
a = (a*a)%mod;
b>>=1;
}
return res;
}
ll gcd(ll x, ll y)
{
if (y==0)
return x;
return gcd(y, x%y);
}
void solve()
{
ll n,k;
cin>>n>>k;
vector<ll>v(n+1);
for (int i=1 ;i <=n ;i++) cin>>v[i];
v[0] = INT_MIN;
sort(v.begin(), v.end());
vector<ll>vec;
for (int i=2 ; i<=n ;i++)
vec.push_back(v[i]-v[i-1]-1);
sort(vec.begin(), vec.end());
ll val = n-k;
ll res = n;
for (int i=1 ; i<=val ; i++)
res += vec[i-1];
cout<<res<<endl;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
ll tt = 1;
// cin>>tt;
while (tt--)
{
solve();
}
return 0;
}
