#include <bits/stdc++.h>
#define pii pair<ll, ll>
typedef long long ll;
using namespace std;
const int MAX = 300003;
ll A[MAX];
pii dp[MAX][2];
const pii operator+(const pii a, const pii b) {
return {a.first + b.first, a.second + b.second};
}
pii Check(ll N, pii p) {
dp[0][0] = {0, 0};
dp[0][1] = {-1e18, 0};
for (int i = 1; i <= N; ++i) {
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
dp[i][1] = max(dp[i - 1][1] + pii{A[i], 0}, dp[i - 1][0] + pii{A[i], 1} + p);
}
return max(dp[N][0], dp[N][1]);
}
int main() {
ios::sync_with_stdio(0); cin.tie(0);
ll N, K;
cin >> N >> K;
for (int i = 1; i <= N; ++i) cin >> A[i];
ll l = 0, r = 1e15;
while (l + 1 < r) {
ll mid = (l + r) >> 1;
pii p = Check(N, pii{-mid, 0});
(p.second < K ? r : l) = mid;
}
pii t = Check(N, pii{-l, 0});
ll ans = t.first + t.second * l;
cout << ans;
return 0;
}
