// Starcraft 2 enjoyer //
#include <bits/stdc++.h>
// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
using namespace std;
#define LSOne(X) ((X) & -(X))
const int N = 3e5 + 5;
const int M = 2e5 + 5;
const int LG = 20;
const int INF = 1e9 + 5;
const int K = 2;
const int C = 26;
const int B = 1000;
const int MOD = 998244353;
long long n, k, a[N], pref[N];
long long ans, cur;
inline void solve()
{
cin >> n >> k;
ans = 0;
cur = 0;
for (int x = 1; x <= n; x++)
{
cin >> a[x];
pref[x] = pref[x - 1] + a[x];
}
if (n / 2 <= k)
{
for (int x = 1; x <= n; x++)
{
if (a[x] > 0)
ans += a[x];
}
cout << ans << "\n";
return;
}
sort(pref, pref + n + 1);
for (int x = 0; x < k; x++)
{
cur += pref[n - x] - pref[x];
ans = max(ans, cur);
}
cout << ans << "\n";
}
signed main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
// cin >> t;
for (int x = 1; x <= t; x++)
{
solve();
}
return 0;
}
