// Om Namah Shivaya
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
using namespace __gnu_pbds;
template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x, y) ((x + y - 1) / (y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl
#define rep(i, n) for(int i = 0; i < n; ++i)
#define rep1(i, n) for(int i = 1; i <= n; ++i)
#define rev(i, s, e) for(int i = s; i >= e; --i)
#define trav(i, a) for(auto &i : a)
template<typename T>
void amin(T &a, T b) {
a = min(a, b);
}
template<typename T>
void amax(T &a, T b) {
a = max(a, b);
}
#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif
/*
refs:
http://www.serbanology.com/vault/The%20Trick%20From%20Aliens
*/
const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;
void solve(int test_case)
{
ll n,k; cin >> n >> k;
vector<ll> a(n+5);
rep1(i,n) cin >> a[i];
vector<ll> pref(n+5);
rep1(i,n) pref[i] = pref[i-1] + a[i];
auto get = [&](ld lambda) -> pair<ld,ll>{
vector<pair<ld,ll>> dp(n+5);
pair<ld,ll> best = {0,0};
rep1(i,n){
// do nothing
dp[i] = dp[i-1];
// put in subarray
pair<ld,ll> px = {pref[i]+best.ff-lambda,best.ss+1};
amax(dp[i],px);
px = {-pref[i]+dp[i].ff,dp[i].ss};
amax(best,px);
}
return dp[n];
};
ld l = 0, r = inf1*n;
ld lambda = -1;
rep(iter,200){
ld mid = (l+r)/2;
if(get(mid).ss <= k){
lambda = mid;
r = mid;
}
else{
l = mid;
}
}
auto [sum,cnt] = get(lambda);
ll ans = sum + cnt*lambda;
cout << ans << endl;
}
int main()
{
fastio;
int t = 1;
// cin >> t;
rep1(i, t) {
solve(i);
}
return 0;
}
