#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using db = double;
const int MAXN = 300005;
const db EPS = 1e-6;
ll n, k;
vector<ll> a, pre;
db dp[MAXN];
int opt[MAXN]; // 0 = skip, 1 = take segment
pair<ll, ll> slv(db mid) {
dp[0] = 0;
opt[0] = 0;
pair<db, ll> best = {0, 0}; // (dp[j] - pre[j], count)
for (ll i = 1; i <= n; ++i) {
db take_val = best.first + pre[i] - mid;
ll take_cnt = best.second + 1;
if (dp[i - 1] > take_val) {
dp[i] = dp[i - 1];
opt[i] = 0;
} else {
dp[i] = take_val;
opt[i] = 1;
}
db candidate_val = dp[i] - pre[i];
ll candidate_cnt = (opt[i] == 1 ? take_cnt : best.second);
if (make_pair(candidate_val, candidate_cnt) > best) {
best = {candidate_val, candidate_cnt};
}
}
// Count segments
ll seg_cnt = 0;
for (ll i = n; i >= 1; --i) {
if (opt[i] == 1) {
seg_cnt++;
while (i > 0 && opt[i] == 1 && dp[i] - pre[i] == dp[i - 1] - pre[i - 1]) i--;
}
}
return {seg_cnt, 0};
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> k;
a.resize(n + 1);
pre.assign(n + 1, 0);
for (ll i = 1; i <= n; ++i) {
cin >> a[i];
pre[i] = pre[i - 1] + a[i];
}
db lo = 0, hi = 1e6;
for (int it = 0; it < 40; ++it) {
db mid = (lo + hi) / 2;
auto [cnt, _] = slv(mid);
if (cnt > k) lo = mid + EPS;
else hi = mid;
}
slv(hi);
cout << dp[n] + hi * k << "\n";
return 0;
}
