///0-0 : what is your motivation, quan606303?
///quan606303 : Hutao
/*idea :
*/
#include <bits/stdc++.h>
#define int long long
#define ll long long
#define INTMAX INT_MAX
#define INTMIN INT_MIN
#define LONGMAX LLONG_MAX
#define LONGMIN LLONG_MIN
#define fi first
#define se second
#define memfull(a,b) memset(a,b,sizeof(a));
#define endl '\n'
#define file(a) freopen(a".inp","r",stdin); freopen(a".out","w",stdout);
using namespace std;
const int MOD=1e9+7;
const int maxn=3e5+7;
pair<int,int> dp[maxn][2];
int a[maxn],n,k;
pair<int,int> solve(int pen)
{
dp[1][0]={0,0};
dp[1][1]={a[1]-pen,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][0].fi+a[i]-pen,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]);
}
int32_t main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
// file("");
cin>>n>>k;
for (int i=1;i<=n;i++)cin>>a[i];
int l=0,r=1e18,ans=0;
while (l<=r)
{
int mid=(l+r)/2;
pair<int,int> cnt=solve(mid);
if (cnt.se<=k)
{
ans=cnt.fi+cnt.se*mid;
r=mid-1;
}
else l=mid+1;
}
cout<<ans;
return 0;
}
