1 #include <bits/stdc++.h>
2 #define _for(i,a,b) for(int i = (a);i < b;i ++)
3 #define _rep(i,a,b) for(int i = (a);i > b;i --)
4 #define INF 0x3f3f3f3f
5 #define MOD 1000000007
6 #define pb push_back
7 #define maxn 500003
8 typedef long long ll;
9 using namespace std;
10 inline ll read()
11 {
12 ll ans = 0;
13 char ch = getchar(), last = ' ';
14 while(!isdigit(ch)) last = ch, ch = getchar();
15 while(isdigit(ch)) ans = (ans << 1) + (ans << 3) + ch - '0', ch = getchar();
16 if(last == '-') ans = -ans;
17 return ans;
18 }
19 inline void write(ll x)
20 {
21 if(x < 0) x = -x, putchar('-');
22 if(x >= 10) write(x / 10);
23 putchar(x % 10 + '0');
24 }
25 ll N,K;
26 struct Tree
27 {
28 ll id;
29 ll val;
30 };
31 struct cmp
32 {
33 bool operator() (const Tree a,const Tree b) const
34 {
35 return a.val < b.val;
36 }
37 };
38 priority_queue<Tree,vector<Tree>,cmp> pq;
39 ll a[maxn];
40 ll l[maxn],r[maxn];
41 ll vis[maxn];
42 ll ans = 0;
43 int main()
44 {
45 N = read();
46 K = read();
47 _for(i,1,N+1)
48 {
49 a[i] = read();
50 l[i] = i-1;r[i] = i+1;
51 pq.push({i,a[i]});
52 }
53
54 _for(i,0,K)
55 {
56 Tree tmp = pq.top();
57 while(vis[tmp.id])
58 {
59 pq.pop();
60 tmp = pq.top();
61 }
62 if(tmp.val<=0)
63 break;
64 pq.pop();
65 ans += tmp.val;
66 pq.push({tmp.id,a[l[tmp.id]]+a[r[tmp.id]]-tmp.val});
67 a[tmp.id] = a[l[tmp.id]]+a[r[tmp.id]]-tmp.val;
68 vis[l[tmp.id]] = vis[r[tmp.id]] = 1;
69 l[tmp.id]=l[l[tmp.id]];r[l[tmp.id]]=tmp.id;
70 r[tmp.id]=r[r[tmp.id]];l[r[tmp.id]]=tmp.id;
71 }
72 write(ans);
73 return 0;
74 }
