#line 1 "a.cpp"
#define PROBLEM "https://yukicoder.me/problems/no/1211"
#line 2 "/home/kuhaku/atcoder/github/algo/lib/template/template.hpp"
#pragma GCC target("sse4.2,avx2,bmi2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
template <class T, class U>
bool chmax(T &a, const U &b) {
    return a < (T)b ? a = (T)b, true : false;
}
template <class T, class U>
bool chmin(T &a, const U &b) {
    return (T)b < a ? a = (T)b, true : false;
}
constexpr std::int64_t INF = 1000000000000000003;
constexpr int Inf = 1000000003;
constexpr int MOD = 1000000007;
constexpr int MOD_N = 998244353;
constexpr double EPS = 1e-7;
constexpr double PI = M_PI;
#line 3 "/home/kuhaku/atcoder/github/algo/lib/graph/graph.hpp"

/**
 * @brief 重み付きグラフ
 *
 * @tparam T 辺の重みの型
 */
template <class T>
struct Graph {
  private:
    struct _edge {
        constexpr _edge() : _from(), _to(), _weight() {}
        constexpr _edge(int from, int to, T weight) : _from(from), _to(to), _weight(weight) {}
        constexpr bool operator<(const _edge &rhs) const { return this->weight() < rhs.weight(); }
        constexpr bool operator>(const _edge &rhs) const { return rhs < *this; }

        constexpr int from() const { return this->_from; }
        constexpr int to() const { return this->_to; }
        constexpr T weight() const { return this->_weight; }

      private:
        int _from, _to;
        T _weight;
    };

  public:
    using edge_type = typename Graph<T>::_edge;

    Graph() : _size(), edges() {}
    Graph(int v) : _size(v), edges(v) {}

    const auto &operator[](int i) const { return this->edges[i]; }
    auto &operator[](int i) { return this->edges[i]; }
    const auto begin() const { return this->edges.begin(); }
    auto begin() { return this->edges.begin(); }
    const auto end() const { return this->edges.end(); }
    auto end() { return this->edges.end(); }
    constexpr int size() const { return this->_size; }

    void add_edge(const edge_type &e) { this->edges[e.from()].emplace_back(e); }
    void add_edge(int from, int to, T weight = T(1)) {
        this->edges[from].emplace_back(from, to, weight);
    }
    void add_edges(int from, int to, T weight = T(1)) {
        this->edges[from].emplace_back(from, to, weight);
        this->edges[to].emplace_back(to, from, weight);
    }

    void input_edge(int m, int base = 1) {
        for (int i = 0; i < m; ++i) {
            int from, to;
            T weight;
            std::cin >> from >> to >> weight;
            this->add_edge(from - base, to - base, weight);
        }
    }
    void input_edges(int m, int base = 1) {
        for (int i = 0; i < m; ++i) {
            int from, to;
            T weight;
            std::cin >> from >> to >> weight;
            this->add_edges(from - base, to - base, weight);
        }
    }

  private:
    int _size;
    std::vector<std::vector<edge_type>> edges;
};

template <>
struct Graph<void> {
  private:
    struct _edge {
        constexpr _edge() : _from(), _to() {}
        constexpr _edge(int from, int to) : _from(from), _to(to) {}

        constexpr int from() const { return this->_from; }
        constexpr int to() const { return this->_to; }
        constexpr int weight() const { return 1; }
        constexpr bool operator<(const _edge &rhs) const { return this->weight() < rhs.weight(); }
        constexpr bool operator>(const _edge &rhs) const { return rhs < *this; }

      private:
        int _from, _to;
    };

  public:
    using edge_type = typename Graph<void>::_edge;

    Graph() : _size(), edges() {}
    Graph(int v) : _size(v), edges(v) {}

    const auto &operator[](int i) const { return this->edges[i]; }
    auto &operator[](int i) { return this->edges[i]; }
    const auto begin() const { return this->edges.begin(); }
    auto begin() { return this->edges.begin(); }
    const auto end() const { return this->edges.end(); }
    auto end() { return this->edges.end(); }
    constexpr int size() const { return this->_size; }

    void add_edge(const edge_type &e) { this->edges[e.from()].emplace_back(e); }
    void add_edge(int from, int to) { this->edges[from].emplace_back(from, to); }
    void add_edges(int from, int to) {
        this->edges[from].emplace_back(from, to);
        this->edges[to].emplace_back(to, from);
    }

    void input_edge(int m, int base = 1) {
        for (int i = 0; i < m; ++i) {
            int from, to;
            std::cin >> from >> to;
            this->add_edge(from - base, to - base);
        }
    }
    void input_edges(int m, int base = 1) {
        for (int i = 0; i < m; ++i) {
            int from, to;
            std::cin >> from >> to;
            this->add_edges(from - base, to - base);
        }
    }

  private:
    int _size;
    std::vector<std::vector<edge_type>> edges;
};
#line 4 "/home/kuhaku/atcoder/github/algo/lib/tree/hld.hpp"

/**
 * @brief HL分解
 * @see https://beet-aizu.github.io/library/tree/heavylightdecomposition.cpp
 */
struct heavy_light_decomposition {
    heavy_light_decomposition() = default;
    template <class T>
    heavy_light_decomposition(const Graph<T> &g, int r = 0) : heavy_light_decomposition(g.size()) {
        build(g, r);
    }

    constexpr int size() const { return _size; }

    int get(int v) const { return vid[v]; }
    int get_parent(int v) const { return par[v]; }
    int get_depth(int v) const { return depth[v]; }

    int dist(int u, int v) const {
        int d = 0;
        while (true) {
            if (vid[u] > vid[v]) std::swap(u, v);
            if (nxt[u] == nxt[v]) return d + vid[v] - vid[u];
            d += vid[v] - vid[nxt[v]] + 1;
            v = par[nxt[v]];
        }
    }

    int jump(int u, int v, int k) const {
        int d = dist(u, v);
        if (d < k) return -1;
        int l = lca(u, v);
        if (dist(u, l) >= k) return la(u, k);
        else return la(v, d - k);
    }

    int la(int v, int k) const {
        while (true) {
            int u = nxt[v];
            if (vid[v] - k >= vid[u]) return inv[vid[v] - k];
            k -= vid[v] - vid[u] + 1;
            v = par[u];
        }
    }

    int lca(int u, int v) const {
        while (true) {
            if (vid[u] > vid[v]) std::swap(u, v);
            if (nxt[u] == nxt[v]) return u;
            v = par[nxt[v]];
        }
    }

    template <class F>
    void for_each(int u, int v, const F &f) const {
        while (true) {
            if (vid[u] > vid[v]) std::swap(u, v);
            f(std::max(vid[nxt[v]], vid[u]), vid[v] + 1);
            if (nxt[u] != nxt[v]) v = par[nxt[v]];
            else break;
        }
    }

    template <class F>
    void for_each_edge(int u, int v, const F &f) const {
        while (true) {
            if (vid[u] > vid[v]) std::swap(u, v);
            if (nxt[u] != nxt[v]) {
                f(vid[nxt[v]], vid[v] + 1);
                v = par[nxt[v]];
            } else {
                if (u != v) f(vid[u] + 1, vid[v] + 1);
                break;
            }
        }
    }

  private:
    int _size;
    std::vector<int> vid, nxt, sub, par, depth, inv;

    heavy_light_decomposition(int n)
        : _size(n), vid(n, -1), nxt(n), sub(n, 1), par(n, -1), depth(n), inv(n) {}

    template <class T>
    void build(const Graph<T> &g, int r = 0) {
        std::vector<int> heavy_path(_size, -1);
        dfs_sz(g, r, heavy_path);
        nxt[r] = r;
        int pos = 0;
        dfs_hld(g, r, pos, heavy_path);
    }

    template <class T>
    void dfs_sz(const Graph<T> &g, int v, std::vector<int> &heavy_path) {
        int max_sub = 0;
        for (auto &e : g[v]) {
            int u = e.to();
            if (u == par[v]) continue;
            par[u] = v;
            depth[u] = depth[v] + 1;
            dfs_sz(g, u, heavy_path);
            sub[v] += sub[u];
            if (chmax(max_sub, sub[u])) heavy_path[v] = u;
        }
    }

    template <class T>
    void dfs_hld(const Graph<T> &g, int v, int &pos, const std::vector<int> &heavy_path) {
        vid[v] = pos++;
        inv[vid[v]] = v;
        int hp = heavy_path[v];
        if (hp != -1) {
            nxt[hp] = nxt[v];
            dfs_hld(g, hp, pos, heavy_path);
        }
        for (auto &e : g[v]) {
            int u = e.to();
            if (u == par[v] || u == heavy_path[v]) continue;
            nxt[u] = u;
            dfs_hld(g, u, pos, heavy_path);
        }
    }
};
#line 2 "/home/kuhaku/atcoder/github/algo/lib/tree/union_find.hpp"

/**
 * @brief 素集合データ構造
 * @details Implement (union by size) + (path compression)
 * @see https://github.com/atcoder/ac-library/blob/master/atcoder/dsu.hpp
 */
struct union_find {
    union_find() : data() {}
    union_find(int _n) : data(_n, -1) {}

    int root(int x) { return this->data[x] < 0 ? x : this->data[x] = this->root(this->data[x]); }
    int get_root(int x) { return this->root(x); }

    bool is_root(int x) const { return this->data[x] < 0; }

    bool same(int x, int y) { return this->root(x) == this->root(y); }
    bool is_same(int x, int y) { return this->same(x, y); }

    int size(int x) { return -(this->data[this->root(x)]); }
    int get_size(int x) { return this->size(x); }

    bool unite(int x, int y) {
        x = this->root(x), y = this->root(y);
        if (x == y) return false;
        if (this->data[x] > this->data[y]) std::swap(x, y);
        this->data[x] += this->data[y];
        this->data[y] = x;
        return true;
    }

    template <class F>
    bool unite(int x, int y, F f) {
        x = this->root(x), y = this->root(y);
        if (x != y) {
            if (this->data[x] > this->data[y]) std::swap(x, y);
            this->data[x] += this->data[y];
            this->data[y] = x;
        }
        f(x, y);
        return x != y;
    }

  private:
    std::vector<int> data;
};
#line 4 "/home/kuhaku/atcoder/github/algo/lib/graph/functional_graph.hpp"

struct functional_graph {
    functional_graph() = default;
    functional_graph(const std::vector<int> &_to) : functional_graph(_to.size(), _to) {
        union_find uf(_size);
        for (int i = 0; i < _size; ++i) {
            assert(0 <= to[i] && to[i] < _size);
            if (!uf.unite(i, to[i])) root[i] = i;
        }
        for (int i = 0; i < _size; ++i) {
            if (root[i] == i) root[uf.root(i)] = root[i];
        }
        for (int i = 0; i < _size; ++i) root[i] = root[uf.root(i)];

        for (int i = 0; i < _size; ++i) {
            if (root[i] == i) g.add_edge(_size, i);
            else g.add_edge(to[i], i);
        }
        hld = heavy_light_decomposition(g, _size);
    }

    constexpr int size() const { return _size; }

    int jump(int v, std::uint64_t step) const {
        int d = hld.get_depth(v);
        if (step <= (std::uint64_t)d - 1) return hld.jump(v, _size, step);
        v = root[v];
        step -= d - 1;
        int bottom = to[v];
        int c = hld.get_depth(bottom);
        step %= c;
        if (step == 0) return v;
        return hld.jump(bottom, _size, step - 1);
    }

    std::vector<int> jump_all(std::uint64_t step) const {
        std::vector<int> res(_size, -1);
        std::vector<std::vector<std::pair<int, int>>> query(_size);
        for (int v = 0; v < _size; ++v) {
            int d = hld.get_depth(v);
            int r = root[v];
            if ((std::uint64_t)d - 1 > step) {
                query[v].emplace_back(v, step);
            } else {
                std::int64_t k = step - (d - 1);
                int bottom = to[r];
                int c = hld.get_depth(bottom);
                k %= c;
                if (k == 0) {
                    res[v] = r;
                    continue;
                }
                query[bottom].emplace_back(v, k - 1);
            }
        }

        std::vector<int> path;
        auto dfs = [&](auto self, int v) -> void {
            path.emplace_back(v);
            for (auto &&[w, k] : query[v]) res[w] = path[path.size() - 1 - k];
            for (auto &&e : g[v]) self(self, e.to());
            path.pop_back();
        };
        for (auto e : g[_size]) dfs(dfs, e.to());
        return res;
    }

    std::vector<std::vector<int>> get_cycles() const {
        std::vector<std::vector<int>> res;
        for (int v = 0; v < _size; ++v) {
            if (v == root[v]) res.emplace_back(get_cycle(v));
        }
        return res;
    }

  private:
    int _size;
    const std::vector<int> &to;
    std::vector<int> root;
    Graph<void> g;
    heavy_light_decomposition hld;

    functional_graph(int n, const std::vector<int> &_to)
        : _size(n), to(_to), root(n, -1), g(n + 1), hld() {}

    std::vector<int> get_cycle(int v) const {
        std::vector<int> res(1, v);
        int u = to[v];
        while (u != v) {
            res.emplace_back(u);
            u = to[u];
        }
        return res;
    }
};
#line 3 "/home/kuhaku/atcoder/github/algo/lib/template/macro.hpp"
#define FOR(i, m, n) for (int i = (m); i < int(n); ++i)
#define FORR(i, m, n) for (int i = (m)-1; i >= int(n); --i)
#define FORL(i, m, n) for (int64_t i = (m); i < int64_t(n); ++i)
#define rep(i, n) FOR (i, 0, n)
#define repn(i, n) FOR (i, 1, n + 1)
#define repr(i, n) FORR (i, n, 0)
#define repnr(i, n) FORR (i, n + 1, 1)
#define all(s) (s).begin(), (s).end()
#line 3 "/home/kuhaku/atcoder/github/algo/lib/template/sonic.hpp"
struct Sonic {
    Sonic() {
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
    }

    constexpr void operator()() const {}
} sonic;
#line 5 "/home/kuhaku/atcoder/github/algo/lib/template/atcoder.hpp"
using namespace std;
using ll = std::int64_t;
using ld = long double;
template <class T, class U>
std::istream &operator>>(std::istream &is, std::pair<T, U> &p) {
    return is >> p.first >> p.second;
}
template <class T>
std::istream &operator>>(std::istream &is, std::vector<T> &v) {
    for (T &i : v) is >> i;
    return is;
}
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
    return os << '(' << p.first << ',' << p.second << ')';
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &v) {
    for (auto it = v.begin(); it != v.end(); ++it) {
        os << (it == v.begin() ? "" : " ") << *it;
    }
    return os;
}
template <class Head, class... Tail>
void co(Head &&head, Tail &&...tail) {
    if constexpr (sizeof...(tail) == 0) std::cout << head << '\n';
    else std::cout << head << ' ', co(std::forward<Tail>(tail)...);
}
template <class Head, class... Tail>
void ce(Head &&head, Tail &&...tail) {
    if constexpr (sizeof...(tail) == 0) std::cerr << head << '\n';
    else std::cerr << head << ' ', ce(std::forward<Tail>(tail)...);
}
template <typename T, typename... Args>
auto make_vector(T x, int arg, Args... args) {
    if constexpr (sizeof...(args) == 0) return std::vector<T>(arg, x);
    else return std::vector(arg, make_vector<T>(x, args...));
}
void setp(int n) {
    std::cout << std::fixed << std::setprecision(n);
}
void Yes(bool is_correct = true) {
    std::cout << (is_correct ? "Yes" : "No") << '\n';
}
void No(bool is_not_correct = true) {
    Yes(!is_not_correct);
}
void YES(bool is_correct = true) {
    std::cout << (is_correct ? "YES" : "NO") << '\n';
}
void NO(bool is_not_correct = true) {
    YES(!is_not_correct);
}
void Takahashi(bool is_correct = true) {
    std::cout << (is_correct ? "Takahashi" : "Aoki") << '\n';
}
void Aoki(bool is_not_correct = true) {
    Takahashi(!is_not_correct);
}
#line 4 "a.cpp"

int main(void) {
    int n, k;
    cin >> n >> k;
    vector<ll> a(n);
    cin >> a;
    auto b = a;
    b.insert(b.begin(), 0);
    b.insert(b.end(), all(a));
    rep (i, n * 2) b[i + 1] += b[i];
    ll l = *min_element(all(a)), r = b[n] + 1;
    vector<int> to(n * 2 + 2, n * 2 + 1);
    while (r - l > 1) {
        ll m = (l + r) / 2;
        int idx = 0;
        rep (i, n * 2) {
            while (idx < (int)b.size() && b[idx] - b[i] < m) ++idx;
            to[i] = idx;
        }
        functional_graph fg(to);
        auto v = fg.jump_all(k);
        bool f = false;
        rep (i, n) {
            if (v[i] - i <= n) {
                f = true;
                break;
            }
        }
        (f ? l : r) = m;
    }
    co(l);

    return 0;
}