#include <bits/stdc++.h>
#define ll long long
using namespace std;
const int mxN = 3e5+5;
int n, k;
ll a[mxN];
int main() {
ios::sync_with_stdio(0), cin.tie(0);
cin >> n >> k;
for (int i = 1; i <= n; i++) cin >> a[i];
auto solve = [&] (ll ld) {
pair <ll, ll> dp[n+1][2];
dp[1][0] = make_pair(0, 0);
dp[1][1] = make_pair(a[1] - ld, 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] - ld, 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]);
};
ll L = 0, R = 1e18, ans = 0;
while (L <= R) {
ll ld = L + (R-L)/2;
pair <ll, ll> v = solve(ld);
if (v.second >= k) ans = ld, L = ld+1;
else R = ld-1;
}
cout << solve(ans).first + ans * k << '\n';
}
