/*
_.-- ,.--.
.' .' /
@ |'..--------._
/ \._/ '.
/ .-.- \
( / \ \
\\ '. | #
\\ \ -. /
:\ | )._____.' \
" | / \ | \ )
| |./' :__ \.-'
'--'
*/
#include<bits/stdc++.h>
#define ll long long
#define llll pair<ll,ll>
#define ii pair<int,int>
#define fi first
#define se second
#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 ull unsigned long long
#define iii pair<int,ii>
#define iv pair<pii,ii>
#define db double
#define ld long double
#define pb push_back
#define tdk "kfph"
#define int long long
using namespace std;
const int dx[] = {1, -1, 0, 0};
const int dy[] = {0, 0, -1, 1};
const int dxx[] = {1, 1, -1, -1, 2, 2, -2, -2};
const int dyy[] = {2, -2, 2, -2, 1, -1, 1, -1};
const ll INF=1e18;
const int N= 3e5+5;
int a[N],n,k;
pair<ll,int> dp[N][2];
pair<ll,int> check(int x)
{
dp[1][1]={a[1]-x,1};
for(int i=2;i<=n;i++)
{
dp[i][0]=max(dp[i-1][0],dp[i-1][1]);
dp[i][1]=max(make_pair(dp[i-1][1].fi+a[i],dp[i-1][1].se),make_pair(dp[i-1][0].fi+a[i]-x,dp[i-1][0].se+1));
}
return max(dp[n][0],dp[n][1]);
}
void kfph()
{
cin >> n >> k;
for(int i=1;i<=n;i++)
{
cin >> a[i];
}
int l=1,r=accumulate(a+1,a+1+n,0ll),ans=0;
while(l<=r)
{
int mid=l+r>>1;
if(check(mid).se>=k)
{
ans=mid;
l=mid+1;
}
else
{
r=mid-1;
}
}
cout << check(ans).fi+ans*k;
}
signed main()
{
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
if(fopen(tdk".inp","r"))
{
freopen(tdk".inp","r",stdin);
freopen(tdk".out","w",stdout);
}
int t=1;
//cin >> t;
while(t--)
{
kfph();
}
return 0;
}
