#include <bits/stdc++.h>
using namespace std;
const int N = 3E5 + 5;
int n, k;
int a[N];
pair<long long, int> dp[N][2];
signed main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
auto calc = [&](long long lambda) {
dp[1][1] = make_pair(a[1] - lambda, 1);
for (int i = 2; i <= n; i++) {
dp[i][0] = max(dp[i - 1][0], dp[i - 1][1]);
auto x = make_pair(dp[i - 1][0].first + a[i] - lambda, dp[i - 1][0].second + 1);
auto y = make_pair(dp[i - 1][1].first + a[i], dp[i - 1][1].second);
dp[i][1] = max(x, y);
}
return max(dp[n][0], dp[n][1]);
};
long long lo = 0;
long long hi = (long long) 1E18;
long long res = 0;
while (lo <= hi) {
long long mid = lo + (hi - lo) / 2;
auto [sum, cnt] = calc(mid);
if (cnt >= k) {
lo = mid + 1;
res = mid;
} else {
hi = mid - 1;
}
}
auto x = calc(res);
// cerr << x.first << ' ' << x.second << ' ' << res << '\n';
cout << x.first + res * k;
return 0;
}
