/* author : Dinmukhammed ^_^ */
#include <map>
#include <set>
#include <unordered_set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <cassert>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <fstream>
#include <unordered_map>
#include <complex>
using namespace std;
#define F first
#define S second
#define sz size()
#define ll long long
#define ld long double
const int N = 4e5+3;
const ll inf = 1e18;
ll a[N] , p[N];
pair <ll , int> dp[N];
int n;
pair <ll , int> get(ll lam){
dp[0] = {0ll , (int)0};
set <pair <ll , int>> st;
pair <ll , int> mx = dp[0];
for(int i = 1; i <= n; i++){
mx = max({dp[i - 1].F - p[i] , dp[i - 1].S} , mx);
dp[i] = mx;
dp[i].F += lam + p[i];
dp[i].S--;
dp[i] = max(dp[i - 1] , dp[i]);
mx = max({dp[i].F - p[i] , dp[i].S} , mx);
}
dp[n].S = -dp[n].S;
return dp[n];
}
void Main(){
ll k; cin >> n >> k;
for(int i = 1; i <= n; i++){
cin >> a[i];
p[i] = p[i - 1] + a[i];
}
ll l = -(ll)1e18 , r = 0 , res = -(ll)1e18;
while(r >= l){
ll md = (r + l) / 2;
if(get(md).S <= k){
res = md;
l = md + 1;
}
else r = md - 1;
}
cout << get(res).F - res * k;
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int tt = 1;
// cin >> tt;
while(tt--) Main();
}
