#include "bits/stdc++.h"
#define sz(x) (int)size(x)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
using namespace std;
using ll = long long;
using pii = pair<int, int>;
const char nl = '\n';
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3f;
int32_t main() {
ios::sync_with_stdio(0), cin.tie(0);
int n, k; cin >> n >> k;
vector<int> a(n); for (auto &x : a) cin >> x;
vector<int> v;
for (int i = 1; i < n; i++)
v.push_back(a[i] - a[i - 1]);
sort(all(v));
ll ans = k;
for (int i = 0; i < n - k; i++)
ans += v[i];
cout << ans << nl;
return 0;
}
