#include <iostream>
#include <algorithm>
#include <queue>
using namespace std;
using ll = long long;
vector <int> t;
struct DSU {
vector <int> link, sz;
vector <ll> mn, mx;
DSU (int s) {
link = sz = vector <int> (s + 1);
mx = mn = vector <ll> (s+1);
for (int i = 1; i <= s; i++) {
link[i] = i;
sz[i] = 1;
mx[i] = mn[i] = t[i];
}
}
int head(int x) {
while (x != link[x])
x = link[x];
return x;
}
bool same(int a, int b) {
return head(a) == head(b);
}
void unite(int a, int b) {
a = head(a);
b = head(b);
if (a == b)
return;
if (sz[a] < sz[b])
swap(a, b);
sz[a] += sz[b];
link[b] = a;
mx[a] = max(mx[a], mx[b]);
mn[a] = min(mn[a], mn[b]);
}
};
int main() {
int n, k;
cin >> n >> k;
t = vector <int> (n+1);
for (int i = 1; i <= n; i++)
cin >> t[i];
DSU dsu(n+1);
priority_queue <pair <ll, pair <int, int>>> pq;
for (int i = 1; i+1 <= n; i++) {
pq.push({-t[i+1] + t[i], {i, i+1}});
}
int cnt = n;
while (cnt > k) {
int a = pq.top().second.first, b = pq.top().second.second;
pq.pop();
if (dsu.same(a, b))
continue;
dsu.unite(a, b);
cnt--;
}
ll ans = 0;
for (int i = 1; i <= n; i++) {
if (i == dsu.head(i)) {
ans += dsu.mx[i] - dsu.mn[i] + 1;
}
}
cout << ans << '\n';
}
