#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using ari2 = array<int, 2>;
using ari3 = array<int, 3>;
using ari4 = array<int, 4>;
using arl2 = array<ll, 2>;
using arl3 = array<ll, 3>;
using arl4 = array<ll, 4>;
#define vt vector
#define all(x) begin(x), end(x)
#define size(x) (int((x).size()))
#define REP(a, b, c, d) for (int a = (b); (d) > 0 ? a <= (c) : a >= (c); a += (d))
#define FOR(a, b, c) REP(a, b, c, 1)
#define ROF(a, b, c) REP(a, b, c, -1)
void solve();
signed main() {
#ifndef DEBUG
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#endif
int T = 1;
//cin >> T;
FOR(t, 1, T) {
solve();
}
}
void solve() {
int N, K;
cin >> N >> K;
vt<int> A(N+1);
FOR(i, 1, N)
cin >> A[i];
vt<array<pair<ld, int>, 2>> dp(N+1);
auto calc = [&](ld pen) {
dp[0][1] = {-3e14, 0};
dp[0][0] = {0, 0};
FOR(i, 1, N) {
dp[i][1] = make_pair(dp[i-1][1].first + A[i], dp[i-1][1].second);
dp[i][1] = max(dp[i][1], make_pair(dp[i-1][0].first + A[i] - pen, dp[i-1][0].second - 1));
dp[i][0] = max(dp[i-1][0], dp[i-1][1]);
}
};
ld lo = 0, hi = 3e14;
FOR(_, 1, 100) {
ld mid = (lo + hi) / 2.0;
calc(mid);
if (-max({dp[N][0], dp[N][1]}).second <= K)
hi = mid;
else
lo = mid;
}
calc(lo);
cout << (ll)round(max(dp[N][0], dp[N][1]).first + lo * K) << '\n';
}
