#include <bits/stdc++.h>
typedef long long ll;
const ll N = 3e5 + 1;
std::pair<ll, ll> dp[N][2];
int main() {
std::ios_base::sync_with_stdio(false);
std::cin.tie(nullptr);
ll n, k;
std::cin >> n >> k;
std::vector<ll> a(n);
for (auto &i : a) {
std::cin >> i;
}
auto solve_dp = [&](ll p) {
dp[0][0] = {0, 0};
dp[0][1] = {a[0] - p, 1};
for (ll i = 1; i < n; ++ i) {
dp[i][1] = std::max(std::make_pair<ll, ll>(a[i] + dp[i - 1][1].first, ll(dp[i - 1][1].second)), std::make_pair<ll, ll>(a[i] + dp[i - 1][0].first - p, dp[i - 1][0].second + 1));
dp[i][0] = std::max(dp[i - 1][0], dp[i - 1][1]);
}
dp[n][0] = std::max(dp[n - 1][0], dp[n - 1][1]);
return dp[n][0];
};
ll lo = 0, hi = 1e18;
for (ll i = 0; i < 64; ++ i) {
ll p = (lo + hi) / 2;
if (solve_dp(p).second <= k) {
hi = p;
} else {
lo = p;
}
}
auto dp = solve_dp(hi);
std::cout << dp.first + dp.second * hi << "\n";
}
