#include <bits/stdc++.h>
using namespace std;
typedef long double LD;
typedef long long LL;
typedef pair <LD, int> PLDI;
constexpr int NMAX = 3e5 + 5;
constexpr LD INF = 1LL * 1e14;
int N, K;
LD A[NMAX];
PLDI dp[NMAX][2];
PLDI Check (LD penalty) {
dp[1][0] = {0, 0};
dp[1][1] = {A[1] - penalty, 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 + A[i] - penalty, dp[i-1][0].second + 1),
make_pair(dp[i-1][1].first + A[i], dp[i-1][1].second));
}
return max(dp[N][0], dp[N][1]);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> N >> K;
for (int i = 1; i <= N; ++ i )
cin >> A[i];
int cnt_op = 100;
LD st = 0, dr = INF;
while (st <= dr && cnt_op) {
LD mij = .5 * (st + dr);
-- cnt_op;
PLDI pos_ans = Check(mij);
if (pos_ans.second >= K)
st = mij;
else dr = mij;
}
PLDI ans = Check(dr);
LL val = round(ans.first + (LD)K * dr);
cout << val << '\n';
return 0;
}
