#include<bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
const int maxN = 1e6 + 5;
const int Mod = 1e9 + 7;
pair<ll, ll> dp[2][maxN];
ll n, k;
ll a[maxN];
void input()
{
cin >> n >> k;
for (int i = 1; i <= n; ++i) cin >> a[i];
}
pair<ll, ll> check(ll x)
{
dp[0][0] = {0, 0};
dp[1][0] = {-x, 1};
//cerr << x << "\n";
for (int i = 1; i <= n; ++i)
{
dp[0][i] = max(dp[1][i - 1], dp[0][i - 1]);
dp[1][i] = max(make_pair(dp[1][i - 1].first + a[i], dp[1][i - 1].second), make_pair(dp[0][i - 1].first + a[i] - x, dp[0][i - 1].second + 1));
}
return max(dp[0][n], dp[1][n]);
}
void solve()
{
ll l = -1e18, r = 1e18;
ll res = 0;
while (l <= r)
{
ll mid = (r + l) / 2;
if (check(mid).second >= k)
{
res = mid;
l = mid + 1;
}
else r = mid - 1;
}
cout << max(check(res).first + k * res, 0ll);
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
//freopen("C.inp","r",stdin);
//freopen("C.out","w",stdout);
input();
solve();
}
