#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(ll i=0;i<(ll)n;i++)
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define spa << " " <<
#define fi first
#define se second
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()

using ld = long double;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<long, long>;
using pdd = pair<ld, ld>;

template<typename T> struct V : vector<T> { using vector<T>::vector; };
V() -> V<ll>;
V(size_t) -> V<ll>;
template<typename T> V(size_t, T) -> V<T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){os << "(" << v.first << ", " << v.second << ")"; return os;}
template<typename T> ostream& operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<vector<T>> &v){ for(auto &e : v){os << e << "\n";} return os;}
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
void fail() { cout << -1 << '\n'; exit(0); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
template<typename T> void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cerr<<v[i][0];for(ll j=1;j<w;j++)cerr spa v[i][j];cerr<<endl;}};
template<typename T> void debug(vector<T>&v,ll n){if(n!=0)cerr<<v[0];
for(ll i=1;i<n;i++)cerr spa v[i];
cerr<<endl;};

const ll INF = (1ll<<62);
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
const ll mod = (int)1e9 + 7;
//const ll mod = 998244353;

ll db[201010][25];
ll nex[201010];
ll S[202020];

int main(){

    ll N, K;
    cin >> N >> K;
    V<ll> A(N);
    REP(i, N) cin >> A[i];

    V<ll> B(2*N);
    REP(i, N){
        B[i] = A[i];
        B[i+N] = A[i];
    }
    // V<ll> S(2*N+1, 0);
    REP(i, 2*N) S[i+1] = S[i] + B[i];

    ll ok = 0;
    ll ng = 1e14;
    ng++;

    while(ng-ok>1){
        ll D = 17;
        ll md = (ok+ng)/2;
        // dump(md)
        // V<ll> next(2*N+2);
        // REP(i, 2*N){
        //     ll pos = lower_bound(ALL(S), S[i]+md) - S.begin();
        //     nex[i] = pos;
        // }
        ll idx = 0;
        REP(i, 2*N){
            while(idx<2*N+1 and S[idx]-S[i]<md) idx++;
            nex[i] = idx;
        }
        nex[2*N] = 2*N;
        nex[2*N+1] = 2*N+1;
        // dump(S)
        // dump(next)
        // V<V<ll>> db(2*N+2, V<ll>(D, 0));
        REP(i, 2*N+2) db[i][0] = nex[i];
        REP(j, D-1){
            REP(i, 2*N+2){
                db[i][j+1] = db[db[i][j]][j];
            }
        }

        bool kanou = false;
        REP(i, min(N, nex[i])){
            ll now = i;
            REP(j, D){
                if(K>>j & 1){
                    now = db[now][j];
                }
            }
            if(now-i<=N){
                kanou = true;
                break;
            }
        }

        // dump(kanou)
        // cerr << endl;
        if(kanou) ok = md;
        else ng = md;
    }

    cout << ok << endl;

    return 0;
}