#include <bits/stdc++.h>
using namespace std;
pair<long long,int> calc(const vector<long long>& a, long long p) {
int n = a.size();
vector<long long> pref(n+1);
for (int i = 0; i < n; i++) pref[i+1] = pref[i] + a[i];
long long dp = 0, best = 0;
int cnt = 0, bestc = 0;
for (int i = 1; i <= n; i++) {
long long v1 = dp;
int c1 = cnt;
long long v2 = best + pref[i] - p;
int c2 = bestc + 1;
if (v2 > v1 || (v2 == v1 && c2 > c1)) {
dp = v2;
cnt = c2;
}
long long cur = dp - pref[i];
if (cur > best || (cur == best && cnt > bestc)) {
best = cur;
bestc = cnt;
}
}
return {dp, cnt};
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
int n, k;
cin >> n >> k;
vector<long long> a(n);
for (auto &x : a) cin >> x;
auto base = calc(a, 0);
if (base.second <= k) {
cout << base.first;
return 0;
}
long long l = 1, r = 1e14;
while (l <= r) {
long long m = (l + r) >> 1;
if (calc(a, m).second > k) l = m + 1;
else r = m - 1;
}
auto res = calc(a, l);
cout << res.first + l * res.second;
}
