#include <bits/stdc++.h>
using namespace std;
void main_program();
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0);
main_program();
}
#define int long long
using ii = pair<int, int>;
int n, k;
vector<int> v, pfx;
ii better(ii a, ii b){
if (a.first != b.first){
return (a.first > b.first) ? a : b;
}
return (a.second < b.second) ? a : b;
}
ii f(int lambda){
vector<ii> dp_closed(n+1), dp_open(n+1);
dp_closed[0] = {0, 0};
dp_open[0] = {0, 0};
for (int i = 1; i <= n; i++){
dp_closed[i] = better(dp_closed[i-1],
{dp_open[i-1].first + pfx[i] - lambda, dp_open[i-1].second + 1});
dp_open[i] = better(dp_open[i-1],
{dp_closed[i].first - pfx[i], dp_closed[i].second});
}
return dp_closed[n];
}
void main_program(){
cin >> n >> k;
v.resize(n+1);
for (int i = 1; i <= n; i++) cin >> v[i];
pfx = v;
for (int i = 1; i <= n; i++) pfx[i] += pfx[i-1];
int l = 0, r = 3e14;
int final = 0;
while (l <= r){
int mid = (l + r) >> 1;
auto res = f(mid);
if (res.second <= k){
r = mid - 1;
final = max(final, res.first + mid * res.second);
}
else l = mid + 1;
}
cout << final << "\n";
}
