#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define endl "\n"
#define ll long long
#define IOS ios_base::sync_with_stdio(false); cin.tie(nullptr);
const int N = 3e5 + 5;
long long a[N];
pair<long long, int> dp[N][2];
pair<long long, int> calc(int n, long long cost) {
dp[0][0] = make_pair(0, 0);
dp[0][1] = make_pair(a[0] - cost, 1);
for (int i = 1; i < n; i++) {
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
dp[i][1] = max(make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second), make_pair(dp[i - 1][0].first + a[i] - cost, dp[i - 1][0].second + 1));
}
return max(dp[n - 1][0], dp[n - 1][1]);
}
int main() {
IOS;
int n, k;
cin >> n >> k;
int ct = 0;
for (int i = 0; i < n; i++) {
cin >> a[i];
if (a[i] > 0) {
ct++;
}
}
k = min(k, ct);
long long l = 0, r = 1e16, opt = 0;
while (l <= r) {
long long mid = (l + r) / 2;
if (calc(n, mid).second >= k) {
opt = mid;
l = mid + 1;
} else {
r = mid - 1;
}
}
long long ans = calc(n, opt).first + opt * k;
cout << ans;
return 0;
}
