#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
// Template
#include <bits/stdc++.h>
#define rep_override(x, y, z, name, ...) name
#define rep2(i, n) for (int i = 0; i < (int)(n); ++i)
#define rep3(i, l, r) for (int i = (int)(l); i < (int)(r); ++i)
#define rep(...) rep_override(__VA_ARGS__, rep3, rep2)(__VA_ARGS__)
#define per(i, n) for (int i = (int)(n) - 1; i >= 0; --i)
#define all(x) (x).begin(), (x).end()
using namespace std;
using ll = long long;
constexpr int inf = 1001001001;
constexpr ll INF = 3003003003003003003;
template <typename T> inline bool chmin(T& x, const T& y) {if (x > y) {x = y; return 1;} return 0;}
template <typename T> inline bool chmax(T& x, const T& y) {if (x < y) {x = y; return 1;} return 0;}
struct IOSET {IOSET() {cin.tie(0); ios::sync_with_stdio(0); cout << fixed << setprecision(10);}} ioset;

int main() {
    int n, k;
    cin >> n >> k;
    vector<ll> a(n);
    rep(i, n) cin >> a[i];
    
    vector<ll> b(2 * n);
    rep(i, n) b[i] = b[i + n] = a[i];
    
    ll s = 0;
    rep(i, n) s += a[i];
    
    vector<int> nxt(3 * n + 1, 3 * n);
    vector<vector<int>> vec(3 * n + 1, vector<int>(20));
    
    auto judge = [&](ll x) -> bool {
        if (s < x) return false;
        {
            int now = 0; ll sum = 0;
            while (sum < x) {
                sum += b[now]; ++now;
            }
            nxt[0] = now;
            rep(i, 1, n) {
                sum -= b[i - 1];
                while (sum < x) {
                    sum += b[now]; ++now;
                }
                nxt[i] = now;
            }
        }
        rep(i, n) nxt[i + n] = nxt[i] + n;
        rep(i, 3 * n + 1) vec[i][0] = nxt[i];
        rep(j, 1, 20) rep(i, 3 * n + 1) vec[i][j] = vec[vec[i][j - 1]][j - 1];
        bool ans = false;
        rep(i, n) {
            int now = i;
            rep(j, 20) {
                if ((k >> j) & 1) now = vec[now][j];
            }
            if (now <= i + n) ans = true;
        }
        return ans;
    };
    
    //judge(4);
    
    ll ok = -1, ng = 1e15;
    while (ng - ok > 1) {
        ll mid = (ng + ok) / 2;
        (judge(mid) ? ok : ng) = mid;
    }
    
    cout << ok << "\n";
    return 0;
}