#include <bits/stdc++.h>
using namespace std;
#define ll long long
int main() {
int n, k;
cin >> n >> k;
int a[n];
for (int &i : a) { cin >> i; }
/**
* @return the maximum sum along with the number of subarrays used
* if creating a subarray penalizes the sum by "lmb" and
* there is no limit to the number of subarrays you can create
*/
auto solve_lambda = [&](ll lmb) {
pair<ll, ll> dp[n][2];
dp[0][0] = {0, 0};
dp[0][1] = {a[0] - lmb, 1};
for (int i = 1; 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 + a[i] - lmb,
dp[i - 1][0].second + 1),
make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
}
return max(dp[n - 1][0], dp[n - 1][1]);
};
ll lo = 0;
ll hi = 1e18;
while (lo < hi) {
ll mid = (lo + hi + 1) / 2;
solve_lambda(mid).second >= k ? lo = mid : hi = mid - 1;
}
cout << solve_lambda(lo).first + lo * k << endl;
}
