#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
#define ll long long
#define pb push_back
#define eb emplace_back
#define pu push
#define ins insert
#define bruh ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ff(x,a,b,c) for (auto x=a;x<=b;x+=c)
#define fd(x,a,b,c) for (auto x=a;x>=b;x-=c)
#define int ll
using namespace std;
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
typedef pair<int, int> ii;
const int N = 3e5+5;
const int mod = 1e9+7;
const int INF = 1e18;
int power(int a,int b) {ll x = 1;if (a >= mod) a%=mod; while (b) {if (b & 1) x = x*a % mod;a = a*a % mod;b>>=1;}return x;}
int n,k;
int a[N];
pair<int,int> calc(int lmb)
{
pair<int,int> dp[n][2];
dp[0][0] = {0,0}; dp[0][1] = {a[0]-lmb,1};
for (int i=1;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].first+a[i],dp[i-1][1].second),make_pair(dp[i-1][0].first+a[i]-lmb,dp[i-1][0].second+1));
}
return max(dp[n-1][0],dp[n-1][1]);
}
void solve()
{
cin>>n>>k;
for (int i=0;i<n;i++) cin>>a[i];
int l = 0,r = 1e18,ans = 0;
while (l<=r)
{
int mid = (l+r)/2;
auto tmp = calc(mid);
if (tmp.second>=k) l = mid+1,ans = mid;
else r = mid-1;
}
//cout<<ans<<endl;
cout<<calc(ans).first+ans*k;
}
signed main()
{
bruh
//freopen("input.inp","r",stdin);
//freopen("output.inp","w",stdout);
int t = 1;
//cin>>t;
while (t--)
{
solve();
cout<<"\n";
}
}
