// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
const int N = 1e5 + 5;
const int M = 1e6 + 5;
const int LG = 60;
const int INF = 1e9 + 5;
const int K = 301;
const int B = 150000;
const int MOD = 1e9 + 7;
int n, k, a[N], dis[N], ans;
inline void solve()
{
cin >> n >> k;
for (int x = 0; x < n; x++)
{
cin >> a[x];
}
sort(a, a + n);
ans = n;
for (int x = 0; x < n - 1; x++)
{
dis[x] = a[x + 1] - a[x];
}
sort(dis, dis + n - 1);
for (int x = 0; x < n - k; x++)
{
ans += dis[x] - 1;
}
cout << ans << "\n";
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
