#include <bits/stdc++.h>
#define int long long
using namespace std;
const int nmax = 2e5 + 1, inf = 1e18;
pair<int, int> dp[nmax][2];
int v[nmax];
int n;
pair<int, int> solve(int lmb) {
dp[1][0] = {0, 0};
dp[1][1] = {v[1] - lmb, 1};
for (int i = 2; i <= n; i++) {
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
dp[i][1] =
max(make_pair(dp[i - 1][0].first + v[i] - lmb, dp[i - 1][0].second + 1),
make_pair(dp[i - 1][1].first + v[i], dp[i - 1][1].second));
}
return max(dp[n][0], dp[n][1]);
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
int k;
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> v[i];
}
int l = 0, r = inf, ans = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (solve(mid).second >= k) {
ans = mid;
l = mid + 1;
} else {
r = mid - 1;
}
}
cout << solve(ans).first + ans * k << '\n';
return 0;
}
