#include <bits/stdc++.h>
using namespace std;
#define int long long
int n;
vector<int> a;
pair<int, int> check(const int lmb) {
vector<vector<pair<int, int>>> dp(n, vector<pair<int, int>> (2));
dp[0] = {{0, 0}, {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(pair(dp[i - 1][0].first + a[i] - lmb, dp[i - 1][0].second + 1),
pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second));
}
return max(dp[n - 1][0], dp[n - 1][1]);
}
signed main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
int k; cin >> n >> k;
a.resize(n);
for (int &x: a)
cin >> x;
int l = -1, r = 2e14;
while (r - l > 1) {
int m = (l + r) / 2;
(check(m).second <= k ? r : l) = m;
}
cout << check(r).first + check(r).second * r << '\n';
}
