/*
* @Author: hungeazy
* @Date: 2025-08-08 22:07:03
* @Last Modified by: hungeazy
* @Last Modified time: 2025-08-08 22:13:57
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,popcnt,lzcnt")
using namespace std;
using namespace __gnu_pbds;
bool M1;
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define int long long
#define ll long long
#define ull unsigned long long
#define sz(x) x.size()
#define sqr(x) (1LL * (x) * (x))
#define all(x) x.begin(), x.end()
#define fill(f,x) memset(f,x,sizeof(f))
#define FOR(i,l,r) for(int i=l;i<=r;i++)
#define FOD(i,r,l) for(int i=r;i>=l;i--)
#define debug(x) cout << #x << " = " << x << '\n'
#define ii pair<int,int>
#define iii pair<int,ii>
#define di pair<ii,ii>
#define vi vector<int>
#define vii vector<ii>
#define mii map<int,int>
#define fi first
#define se second
#define pb push_back
#define MOD 1000000007
#define __lcm(a,b) (1ll * ((a) / __gcd((a), (b))) * (b))
#define YES cout << "YES\n"
#define NO cout << "NO\n"
#define MASK(i) (1LL << (i))
#define c_bit(i) __builtin_popcountll(i)
#define BIT(x,i) ((x) & MASK(i))
#define SET_ON(x,i) ((x) | MASK(i))
#define SET_OFF(x,i) ((x) & ~MASK(i))
#define oo 1e18
#define name ""
#define endl '\n'
#define memory() cerr << abs(&M2-&M1)/1024.0/1024 << " MB" << endl
#define time() cerr << endl << "-------------Time:" << 1000.0 * clock() / CLOCKS_PER_SEC << "ms." << endl
template<typename T> bool maximize(T &res, const T &val) { if (res < val){ res = val; return true; }; return false; }
template<typename T> bool minimize(T &res, const T &val) { if (res > val){ res = val; return true; }; return false; }
template <class T> using ordered_set = tree <T, null_type, less_equal <T>, rb_tree_tag,tree_order_statistics_node_update>;
const int N = (int)3e5+10;
int n,k,a[N];
namespace hungeazy {
ii dp[N][2];
ii calc(int lambda)
{
dp[0][1] = {-oo,-oo};
FOR(i,1,n)
{
dp[i][0] = max(dp[i-1][0],dp[i-1][1]);
dp[i][1] = max(make_pair(dp[i-1][0].fi+a[i]-lambda,dp[i-1][0].se+1),
make_pair(dp[i-1][1].fi+a[i],dp[i-1][1].se));
}
return max(dp[n][0],dp[n][1]);
}
void solve(void)
{
int l = 1, r = 1e18, ans = 0;
while (l <= r)
{
int mid = (l+r)>>1;
if (calc(mid).se >= k) ans = mid, l = mid+1;
else r = mid-1;
}
cout << calc(ans).fi+k*ans;
}
}
bool M2;
signed main()
{
fast;
if (fopen(name".inp","r"))
{
freopen(name".inp","r",stdin);
freopen(name".out","w",stdout);
}
cin >> n >> k;
FOR(i,1,n) cin >> a[i];
hungeazy::solve();
time();
memory();
return 0;
}
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