#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
#define pb push_back
#define all(a) a.begin(),a.end()
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef unsigned long long ull;
typedef vector<int> vi;
const int mxn = 3e5;
int arr[mxn];
pair<ll,int> dp[mxn][2];
int n,k;
pair<ll,int> get(ll lambda){
dp[0][0] = {0,0};
dp[0][1] = {arr[0]-lambda,1};
for(int i = 1; i < n; i++){
dp[i][0] = max(dp[i-1][0],dp[i-1][1]);
dp[i][1] = max(pair<ll,int>{dp[i-1][0].first+arr[i]-lambda,dp[i-1][0].second+1},
pair<ll,int>{dp[i-1][1].first+arr[i],dp[i-1][1].second});
}
return max(dp[n-1][0],dp[n-1][1]);
}
void solve(){
cin >> n >> k;
for(int i = 0; i < n; i++)
cin >> arr[i];
ll l = 0, r = 1e15;
while(l+1 < r){
ll mid = (l+r)>>1;
auto [ans,res] = get(mid);
if(res >= k) l = mid;
else r = mid;
}
cout << get(l).first + k*l;
}
signed main(){
cin.tie(0)->sync_with_stdio(0);
int t = 1;
// cin >> t;
while(t--){solve();}
}
