// competitive-verifier: PROBLEM
#ifdef ATCODER
#pragma GCC target("sse4.2,avx512f,avx512dq,avx512ifma,avx512cd,avx512bw,avx512vl,bmi2")
#endif
#pragma GCC optimize("Ofast,fast-math,unroll-all-loops")
#pragma GCC target("sse4.2,avx2,bmi2")
#include <bits/stdc++.h>
#ifndef ATCODER
#endif
template <class T, class U>
constexpr bool chmax(T &a, const U &b)
{
    return a < (T)b ? a = (T)b, true : false;
}
template <class T, class U>
constexpr 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 double EPS = 1e-7;
constexpr double PI = 3.14159265358979323846;
#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()
struct Sonic
{
    Sonic()
    {
        std::ios::sync_with_stdio(false);
        std::cin.tie(nullptr);
        std::cout << std::fixed << std::setprecision(20);
    }
    constexpr void operator()() const {}
} sonic;
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)...);
}
void Yes(bool is_correct = true) { std::cout << (is_correct ? "Yes\n" : "No\n"); }
void No(bool is_not_correct = true) { Yes(!is_not_correct); }
void YES(bool is_correct = true) { std::cout << (is_correct ? "YES\n" : "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); }
namespace internal
{
    struct graph_csr
    {
    private:
        struct edge_list
        {
            using const_iterator = std::vector<int>::const_iterator;
            edge_list(const graph_csr &g, int v) : g(g), v(v) {}
            const_iterator begin() const { return std::next(g.elist.begin(), g.start[v]); }
            const_iterator end() const { return std::next(g.elist.begin(), g.start[v + 1]); }

        private:
            const graph_csr &g;
            int v;
        };

    public:
        graph_csr(int n) : _size(n), edges(), start(n + 1) {}
        edge_list operator[](int i) const { return edge_list(*this, i); }
        constexpr int size() const { return _size; }
        void build()
        {
            for (auto [u, v] : edges)
                ++start[u + 1];
            for (int i = 0; i < _size; ++i)
                start[i + 1] += start[i];
            auto counter = start;
            elist = std::vector<int>(edges.size());
            for (auto [u, v] : edges)
                elist[counter[u]++] = v;
        }
        void add_edge(int u, int v) { edges.emplace_back(u, v); }
        void add_edges(int u, int v)
        {
            edges.emplace_back(u, v);
            edges.emplace_back(v, u);
        }
        void input_edge(int m, int base = 1)
        {
            for (int i = 0; i < m; ++i)
            {
                int from, to;
                std::cin >> from >> to;
                add_edge(from - base, to - base);
            }
            build();
        }
        void input_edges(int m, int base = 1)
        {
            for (int i = 0; i < m; ++i)
            {
                int from, to;
                std::cin >> from >> to;
                add_edges(from - base, to - base);
            }
            build();
        }
        int _size;
        std::vector<std::pair<int, int>> edges;
        std::vector<int> elist;
        std::vector<int> start;
    };
} // namespace internal
/**
 * @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 weight() < rhs.weight(); }
        constexpr bool operator>(const _edge &rhs) const { return rhs < *this; }
        constexpr int from() const { return _from; }
        constexpr int to() const { return _to; }
        constexpr T weight() const { return _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 edges[i]; }
    auto &operator[](int i) { return edges[i]; }
    const auto begin() const { return edges.begin(); }
    auto begin() { return edges.begin(); }
    const auto end() const { return edges.end(); }
    auto end() { return edges.end(); }
    constexpr int size() const { return _size; }
    void add_edge(const edge_type &e) { edges[e.from()].emplace_back(e); }
    void add_edge(int from, int to, T weight = T(1)) { edges[from].emplace_back(from, to, weight); }
    void add_edges(int from, int to, T weight = T(1))
    {
        edges[from].emplace_back(from, to, weight);
        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;
            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;
            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 _from; }
        constexpr int to() const { return _to; }
        constexpr int weight() const { return 1; }
        constexpr bool operator<(const _edge &rhs) const { return 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 edges[i]; }
    auto &operator[](int i) { return edges[i]; }
    const auto begin() const { return edges.begin(); }
    auto begin() { return edges.begin(); }
    const auto end() const { return edges.end(); }
    auto end() { return edges.end(); }
    constexpr int size() const { return _size; }
    void add_edge(const edge_type &e) { edges[e.from()].emplace_back(e); }
    void add_edge(int from, int to) { edges[from].emplace_back(from, to); }
    void add_edges(int from, int to)
    {
        edges[from].emplace_back(from, to);
        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;
            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;
            add_edges(from - base, to - base);
        }
    }

private:
    int _size;
    std::vector<std::vector<edge_type>> edges;
};
/**
 * @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())
    {
        std::vector<int> heavy_path(_size, -1), sub_size(_size, 1);
        std::stack<int> st;
        st.emplace(r);
        int pos = 0;
        while (!st.empty())
        {
            int v = st.top();
            st.pop();
            vid[pos++] = v;
            for (auto &e : g[v])
            {
                int u = e.to();
                if (u == par[v])
                    continue;
                par[u] = v, dep[u] = dep[v] + 1, st.emplace(u);
            }
        }
        for (int i = _size - 1; i >= 0; --i)
        {
            int v = vid[i];
            int max_sub = 0;
            for (auto &e : g[v])
            {
                int u = e.to();
                if (u == par[v])
                    continue;
                sub_size[v] += sub_size[u];
                if (max_sub < sub_size[u])
                    max_sub = sub_size[u], heavy_path[v] = u;
            }
        }
        nxt[r] = r;
        pos = 0;
        st.emplace(r);
        while (!st.empty())
        {
            int v = st.top();
            st.pop();
            vid[v] = pos++;
            inv[vid[v]] = v;
            int hp = heavy_path[v];
            for (auto &e : g[v])
            {
                int u = e.to();
                if (u == par[v] || u == hp)
                    continue;
                nxt[u] = u, st.emplace(u);
            }
            if (hp != -1)
                nxt[hp] = nxt[v], st.emplace(hp);
        }
    }
    heavy_light_decomposition(const internal::graph_csr &g, int r = 0)
        : heavy_light_decomposition(g.size())
    {
        std::vector<int> heavy_path(_size, -1), sub_size(_size, 1);
        std::stack<int> st;
        st.emplace(r);
        int pos = 0;
        while (!st.empty())
        {
            int v = st.top();
            st.pop();
            vid[pos++] = v;
            for (int u : g[v])
            {
                if (u == par[v])
                    continue;
                par[u] = v, dep[u] = dep[v] + 1, st.emplace(u);
            }
        }
        for (int i = _size - 1; i >= 0; --i)
        {
            int v = vid[i];
            int max_sub = 0;
            for (int u : g[v])
            {
                if (u == par[v])
                    continue;
                sub_size[v] += sub_size[u];
                if (max_sub < sub_size[u])
                    max_sub = sub_size[u], heavy_path[v] = u;
            }
        }
        nxt[r] = r;
        pos = 0;
        st.emplace(r);
        while (!st.empty())
        {
            int v = st.top();
            st.pop();
            vid[v] = pos++;
            inv[vid[v]] = v;
            int hp = heavy_path[v];
            for (int u : g[v])
            {
                if (u == par[v] || u == hp)
                    continue;
                nxt[u] = u, st.emplace(u);
            }
            if (hp != -1)
                nxt[hp] = nxt[v], st.emplace(hp);
        }
    }
    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 dep[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, par, dep, inv;
    heavy_light_decomposition(int n) : _size(n), vid(n, -1), nxt(n), par(n, -1), dep(n), inv(n) {}
};
/**
 * @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() = default;
    explicit union_find(int _n) : _rank(_n), data(_n, -1) {}
    const int &operator[](std::size_t x) const { return data[x]; }
    int &operator[](std::size_t x) { return data[x]; }
    int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); }
    int get_root(int x) { return root(x); }
    bool is_root(int x) const { return data[x] < 0; }
    bool same(int x, int y) { return root(x) == root(y); }
    bool is_same(int x, int y) { return same(x, y); }
    int rank() { return _rank; }
    int size(int x) { return -(data[root(x)]); }
    int get_size(int x) { return size(x); }
    std::vector<int> leaders()
    {
        std::vector<int> res;
        for (int i = 0; i < (int)data.size(); ++i)
        {
            if (is_root(i))
                res.emplace_back(i);
        }
        return res;
    }
    bool unite(int x, int y)
    {
        x = root(x), y = root(y);
        if (x == y)
            return false;
        --_rank;
        if (data[x] > data[y])
            std::swap(x, y);
        data[x] += data[y];
        data[y] = x;
        return true;
    }
    template <class F>
    bool unite(int x, int y, F f)
    {
        x = root(x), y = root(y);
        if (x != y)
        {
            if (data[x] > data[y])
                std::swap(x, y);
            data[x] += data[y];
            data[y] = x;
        }
        f(x, y);
        return x != y;
    }

private:
    int _rank;
    std::vector<int> data;
};
/// @brief functional graph
struct functional_graph
{
    functional_graph() = default;
    functional_graph(const std::vector<int> &_to) : functional_graph(_to.size(), _to)
    {
        std::vector<bool> is_root(_size);
        for (int i = 0; i < _size; ++i)
        {
            int x = i;
            while (root[x] == -1)
            {
                root[x] = i;
                x = to[x];
            }
            if (root[x] == i)
                is_root[x] = true;
            int r = (is_root[x] ? x : root[x]);
            x = i;
            while (r != i && root[x] == i)
            {
                root[x] = r;
                x = to[x];
            }
        }
        for (int i = 0; i < _size; ++i)
        {
            if (is_root[i])
                g.add_edge(_size, i);
            else
                g.add_edge(to[i], i);
        }
        g.build();
        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::pair<int, int>> query;
        internal::graph_csr csr(_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)
            {
                csr.add_edge(v, query.size());
                query.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;
                }
                csr.add_edge(bottom, query.size());
                query.emplace_back(v, k - 1);
            }
        }
        csr.build();
        std::vector<int> path;
        auto dfs = [&](auto self, int v) -> void
        {
            path.emplace_back(v);
            for (int id : csr[v])
                res[query[id].first] = path[path.size() - 1 - query[id].second];
            for (int u : g[v])
                self(self, u);
            path.pop_back();
        };
        for (int u : g[_size])
            dfs(dfs, u);
        return res;
    }
    int dist(int u, int v)
    {
        if (root[u] != root[v])
            return -1;
        if (u == v)
            return 0;
        int du = hld.get_depth(u);
        int dv = hld.get_depth(v);
        if (du > dv)
            return du - dv;
        int c = hld.get_depth(to[root[u]]);
        return dv > c ? -1 : c - dv + du;
    }
    int cycle(int v) const
    {
        v = root[v];
        return hld.get_depth(to[v]);
    }
    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;
    internal::graph_csr 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;
    }
};
int main(void)
{
    int n, k;
    cin >> n >> k;
    vector<ll> a(n);
    cin >> a;
    rep(i, n) a.emplace_back(a[i]);
    a.emplace_back(0);
    repr(i, n * 2) a[i] += a[i + 1];
    ll l = 1, r = a[n] / k + 1;
    vector<int> to(n * 2 + 2, n * 2 + 1);
    while (r - l > 1)
    {
        ll m = (l + r) / 2;
        int idx = 2 * n;
        repr(i, n * 2)
        {
            while (a[i] - a[idx - 1] >= 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;
}