#include<bits/stdc++.h>
using namespace std;
#define foru(i,a,b) for(int i=(a); i<=(b); ++i)
#define ford(i,a,b) for(int i=(a); i>=(b); --i)
#define rep(i,a) for(int i=0; i<(a); ++i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(),(a).end()
#define bit(s,i) (((s)>>(i))&1)
#define ii pair<int,int>
#define vi vector<int>
#define vii vector<ii>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
#define _ << " " <<
template <class X, class Y> bool maxi(X &x, Y y){return x<y?x=y,true:false;}
template <class X, class Y> bool mini(X &x, Y y){return x>y?x=y,true:false;}
const int N=3e5+5;
int n,k,a[N];
struct Node{
ll mx; int l, r; /// max trong doan
ll mxp; int p; /// max prefix
ll mxs; int s; /// max suffix
ll sum;
/// cac doan co it nhat 1 phan tu
Node(){
mx=mxp=mxs=sum=0;
l=r=p=s=0;
}
} stP[N<<2], stN[N<<2];
Node comb(Node a, Node b){
Node c;
c.mx=max(max(a.mx,b.mx),a.mxs+b.mxp);
if(c.mx==a.mx) c.l=a.l, c.r=a.r;
else if(c.mx==b.mx) c.l=b.l, c.r=b.r;
else c.l=a.s, c.r=b.p;
c.mxp=max(a.mxp, a.sum+b.mxp);
if(c.mxp==a.mxp) c.p=a.p;
else c.p=b.p;
c.mxs=max(b.mxs, b.sum+a.mxs);
if(c.mxs==b.mxs) c.s=b.s;
else c.s=a.s;
c.sum=a.sum+b.sum;
return c;
}
#define lc id<<1
#define rc id<<1|1
void build(int id=1, int l=1, int r=n){
if(l==r){
stP[id].mx=stP[id].mxp=stP[id].mxs=stP[id].sum=a[l];
stP[id].l=stP[id].r=stP[id].p=stP[id].s=l;
stN[id].mx=stN[id].mxp=stN[id].mxs=stN[id].sum=-a[l];
stN[id].l=stN[id].r=stN[id].p=stN[id].s=l;
return;
}
int mid=(l+r)>>1;
build(lc,l,mid);
build(rc,mid+1,r);
stP[id]=comb(stP[lc],stP[rc]);
stN[id]=comb(stN[lc],stN[rc]);
}
int lz[N<<2];
void apply(int id){
lz[id]^=1;
swap(stP[id],stN[id]);
}
void down(int id){
if(lz[id]==0)return;
apply(lc); apply(rc);
lz[id]=0;
}
void upd(int u, int v, int id=1, int l=1, int r=n){
if(u>r||v<l)return;
if(u<=l&&r<=v){
apply(id);
return;
}
int mid=(l+r)>>1;
down(id);
upd(u,v,lc,l,mid);
upd(u,v,rc,mid+1,r);
stP[id]=comb(stP[lc],stP[rc]);
stN[id]=comb(stN[lc],stN[rc]);
}
void solve(){
cin>>n>>k;
foru(i,1,n) cin>>a[i];
build();
ll res=0, cur=0;
foru(i,1,k){
int l=stP[1].l, r=stP[1].r;
cur+=stP[1].mx;
upd(l,r);
maxi(res,cur);
}
cout<<res<<'\n';
}
int32_t main(){
#define task "test"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc=1; //cin>>tc;
foru(i,1,tc){
solve();
}
}
