#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
int n, k;
vector<ll> a;
const ll INF = 1e18;
pair<ll, int> check(ll cost) {
vector<array<pair<ll, int>, 2>> dp(n + 1);
dp[1][0] = {0, 0};
dp[1][1] = {a[0] - cost, 1};
for (int i = 2; i <= n; i++) {
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
dp[i][1] =
max(pair<ll, int>{dp[i - 1][0].first + a[i - 1] - cost,
dp[i - 1][0].second + 1},
pair<ll, int>{dp[i - 1][1].first + a[i - 1], dp[i - 1][1].second});
}
return max(dp[n][0], dp[n][1]);
}
int main() {
ios::sync_with_stdio(false);
cin.tie(nullptr), cout.tie(nullptr);
cin >> n >> k;
a.resize(n);
for (int i = 0; i < n; i++)
cin >> a[i];
ll left = 0, right = INF;
while (right - left > 1) {
ll mid = (left + right) / 2;
if (check(mid).second >= k)
left = mid;
else
right = mid;
}
cout << check(left).first + left * k << endl;
}
