/*==============================================================================================================
__ __ _____ ______ _______
| | | | / __ \ / _____| / ______|
__| |__ __| |__ |_| | | | | | |
|__| __| |__| __| | | | |____ | |_____
| | _____ _ | | ____ __ __ ____ _____ _____ / / \ ___ \ | ___ \
| | / _ \ | | | | / _/ | | | | / _ \ / __ \ / _ \ / / | | | | | |
| |_ | |_| | | | | |_ | | | |_| | | |_| | | | | | | |_| | / /___ ____| | | |___| |
\____\ \____/| |_| \____\ |_| \_____/ \_____/ |_| |_| \____ | |______| |______/ \_______/
| |
__/ |
|___/
Pratice, practice, and practice
Where is the bug, delete it there
Try, try, try again until you succeed
I hated every minute of training, but I said, 'Don't quit. Suffer now and live the rest of your life as a champion.' - Mohamed Ali
You may not be the best, but must be the most effort
Even the things and people you like, you don't have the courage to take, you are destined to be a failure.
Difficult means more time
Done is better than perfect
Pain + Reflection = Progress
==============================================================================================================*/
#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ld long double
#define endl '\n'
const ll mod = 1e9+7;
ll n, k, a[300005];
pair<ld, ll> dp[300005][3]; //sum doan, cnt doan
ld l, r, lambda;
bool check(ld m)
{
dp[0][0]={0, 0};
dp[0][1]={-1e18, 0};
for (ll 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][1].first+a[i], dp[i-1][1].second), //them a[i] vao doan truoc do
make_pair(dp[i-1][0].first+a[i]-m, dp[i-1][0].second+1)); // bat dau doan moi tai vi tri a[i]
}
return max(dp[n][0], dp[n][1]).second>=k;
}
void solve()
{
cin>>n>>k;
for (ll i=1; i<=n; i++) cin>>a[i];
l=0, r=1e18;
ld eps=1e-6;
while (r-l>eps)
{
ld mid=(l+r)/2;
if (check(mid)==true) l=mid;
else r=mid;
}
lambda=l;
check(lambda);
cout<<llround(max(dp[n][0], dp[n][1]).first+lambda*k);
}
int main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL);
clock_t start = clock();
//#ifndef ONLINE_JUDGE
//freopen("_input.txt", "r", stdin);
//freopen("_output.txt", "w", stdout);
//#endif
solve();
clock_t end = clock();
cerr<<"Time: "<<fixed<<setprecision(10)<<double(end-start)/double(CLOCKS_PER_SEC)<<"\n";
return 0;
}
