#include<bits/stdc++.h>
using namespace std;
#define TASK "bai3"
#define rep(i,x,y) for(int i=(x);i<=(y);++i)
template<class T> bool maximize(T &a, const T &b){ return (a < b) ? a = b, 1 : 0; }
template<class T> bool minimize(T &a, const T &b){ return (a > b) ? a = b, 1 : 0; }
typedef long long ll;
#define all(x) x.begin(),x.end()
#define ii pair<int,int>
#define fi first
#define se second
#define pb push_back
// end of template
const int N = 3e5 + 5;
int n,k,a[N];
pair<ll,int> dp[N][2];
pair<ll,int> work(ll slope)
{
rep(i,0,n) dp[i][0]=dp[i][1]={0,0};
rep(i,0,n-1)
{
maximize(dp[i+1][0],max(dp[i][0],dp[i][1]));
maximize(dp[i+1][1],make_pair(dp[i][1].fi+a[i+1],dp[i][1].se));
rep(j,0,1)
{
maximize(dp[i+1][1],make_pair(dp[i][j].fi+a[i+1]-slope,dp[i][j].se+1));
}
}
return max(dp[n][0],dp[n][1]);
}
void solve()
{
cin>>n>>k;
rep(i,1,n) cin>>a[i];
ll lo=0,hi=1e18,mid,cm=0;
while(lo<=hi)
{
mid=(lo+hi)>>1;
if(work(mid).se>=k) cm=mid,lo=mid+1;
else hi=mid-1;
}
cout<<work(cm).fi+cm*k;
}
int main(void)
{
// freopen(TASK".inp","r",stdin);
// freopen(TASK".out","w",stdout);
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int testcase=1;
// cin>>testcase;
while(testcase--)
solve();
return 0;
}
