#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<ll, ll>;
const ll INF = LLONG_MAX / 2;
const int iINF = INT_MAX / 2;
const int MAXN = 3e5 + 5;
int n, k;
ll arr[MAXN], dp[MAXN][2];
int cnt[MAXN][2];
pll eval(ll c)
{
dp[0][1] = -INF;
for (int i = 1; i <= n; i++)
{
if (dp[i - 1][0] >= dp[i - 1][1])
{
dp[i][0] = dp[i - 1][0];
cnt[i][0] = cnt[i - 1][0];
}
else
{
dp[i][0] = dp[i - 1][1];
cnt[i][0] = cnt[i - 1][1];
}
if (dp[i - 1][0] - c >= dp[i - 1][1])
{
dp[i][1] = arr[i] + dp[i - 1][0] - c;
cnt[i][1] = cnt[i - 1][0] + 1;
}
else
{
dp[i][1] = arr[i] + dp[i - 1][1];
cnt[i][1] = cnt[i - 1][1];
}
}
return max(pll(dp[n][0], cnt[n][0]), pll(dp[n][1], cnt[n][1]));
}
void solve()
{
cin >> n >> k;
for (int i = 1; i <= n; i++)
cin >> arr[i];
ll answer = 0;
ll lo = 0, hi = INF;
while (lo <= hi)
{
ll mi = lo + (hi - lo) / 2;
auto [optv, optc] = eval(mi);
if (optc <= k)
hi = mi - 1, answer = max(answer, optv + optc * mi);
else
lo = mi + 1;
}
cout << answer << '\n';
}
int main()
{
ios_base::sync_with_stdio(false), cin.tie(0);
int t = 1;
// cin >> t;
while (t--) solve();
return 0;
}
