#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pll = pair<long long, long long>;
const int N = 3e5 + 10;
ll n, k, a[N];
pll dp[N][2];
pll solve(ll lambda) {
for (int i = 1; i <= n; i++) dp[i][0] = dp[i][1] = {0, 0};
dp[1][0] = {0, 0};
dp[1][1] = {a[1] - lambda, 1};
for (int i = 2; i <= n; i++) {
dp[i][0] = max(dp[i-1][0], dp[i-1][1]);
dp[i][1] = max(make_pair(dp[i-1][0].first + a[i] - lambda, dp[i-1][0].second + 1),
make_pair(dp[i-1][1].first + a[i], dp[i-1][1].second));
}
return max(dp[n][0], dp[n][1]);
}
int main() {
cin.tie(nullptr)->ios_base::sync_with_stdio(false);
cin >> n >> k;
for (int i = 1; i <= n; i++) cin >> a[i];
ll b = 0, e = 1e18;
while (b < e) {
ll mid = (b + e + 1) / 2;
if (solve(mid).second >= k) b = mid;
else e = mid - 1;
}
cout << solve(b).first + b * k;
}
