#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pii = pair<int, int>;
using pll = pair<long long, long long>;
using ull = unsigned long long;
#define X first
#define Y second
#define SZ(x) int(x.size())
#define all(x) x.begin(), x.end()
#define mins(a,b) (a = min(a,b))
#define maxs(a,b) (a = max(a,b))
#define pb push_back
#define Mp make_pair
#define lc id<<1
#define rc lc|1
// #define mid ((l+r)/2)
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
const ll INF = 1e9 + 23;
const ll MOD = 1e9 + 7;
const int MXN = 3e5 + 5;
const int LOG = 23;
int n, k, a[MXN];
pll calc(ll lmb) {
pll mx = Mp(0, 0), ans = mx;
ll sum=0;
for(int i=1; i<=n; i++) {
sum += a[i];
maxs(ans, Mp(mx.X+sum-lmb, mx.Y+1));
maxs(mx, Mp(ans.X-sum, ans.Y));
}
return ans;
}
void Main() {
cin >> n >> k;
for(int i=1; i<=n; i++) cin >> a[i];
// ll l=-1, r=1e18;
// while(r-l>1)
// (calc(mid).Y>=k ? l : r) = mid;
// cout << calc(l).X + l*k << '\n';
ll lo = 0;
ll hi = 1e18;
while (lo < hi) {
ll mid = (lo + hi + 1) / 2;
calc(mid).second >= k ? lo = mid : hi = mid - 1;
}
cout << calc(lo).first + lo * k << endl;
}
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
int T = 1;
// cin >> T;
while(T--) Main();
return 0;
}
