#include <bits/stdc++.h>
using namespace std;
template <class F> class y_combinator {
    F f;

   public:
    y_combinator(F&& f) : f(std::forward<F>(f)) {}
    template <class... Args> auto operator()(Args&&... args) const { return f(*this, std::forward<Args>(args)...); }
};
using ll = long long;
using ld = long double;
using u8 = uint8_t;
using u32 = uint32_t;
using u64 = uint64_t;
using vi = vector<int>;
using vl = vector<ll>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template <class T, class U = std::less<T>> using prique = std::priority_queue<T, std::vector<T>, U>;
inline constexpr int popcnt(u64 x) noexcept { return __builtin_popcountll(x); }
template <class T> T floor(T a, T b) noexcept { return a / b - (a % b && (a ^ b) < 0); }
template <class T> T ceil(T a, T b) noexcept { return floor(a + b - 1, b); }
template <class T> bool chmin(T& x, const T& y) noexcept { return (x > y ? x = y, true : false); }
template <class T> bool chmax(T& x, const T& y) noexcept { return (x < y ? x = y, true : false); }
template <class T> void dedup(std::vector<T>& v) { std::sort(std::begin(v), std::end(v)), v.erase(std::unique(std::begin(v), std::end(v)), std::end(v)); }
void SCAN() {}
template <class H, class... T> void SCAN(H& h, T&... t) { std::cin >> h, SCAN(t...); }
#define INT(...) int __VA_ARGS__; SCAN(__VA_ARGS__)
#define LL(...) long long __VA_ARGS__; SCAN(__VA_ARGS__)
#define LD(...) long double __VA_ARGS__; SCAN(__VA_ARGS__)
#define STR(...) std::string __VA_ARGS__; SCAN(__VA_ARGS__)
#define CHAR(...) char __VA_ARGS__; SCAN(__VA_ARGS__)
#define VEC(type, name, size) std::vector<type> name(size); for (int i = 0; i < (int)size; i++) SCAN(name[i]);
#define VV(type, name, h, w) std::vector<std::vector<type>> name(h, std::vector<type>(w)); for (int i = 0; i < (int)h; i++) for (int j = 0; j < (int)w; j++) SCAN(name[i][j]);
#define overload4(a, b, c, d, e, ...) e
#define rep1(a) for (long long _i = 0; _i < (a); _i++)
#define rep2(i, a) for (long long i = 0; i < (a); i++)
#define rep3(i, a, b) for (long long i = (a); i < (b); i++)
#define rep4(i, a, b, c) for (long long i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep(i, a, b, c) for (long long i = (a); i > (b); i += (c))
#define all(x) std::begin(x), std::end(x)
#define rall(x) std::rbegin(x), std::rend(x)
#define len(x) (long long)(size(x))
#define pb push_back
#ifndef LOCAL
#define debug(...)
#endif

#include <atcoder/modint>
using mint = atcoder::modint;
void run_case() {
    INT(N, K);
    VEC(ll, A, N);
    vector<ll> S(N + N + 1);
    rep(i, N * 2) S[i + 1] = S[i] + A[i % N];
    const int LOG = 20;
    auto Make = [&](ll X) {
        vector<vector<int>> table(LOG, vector<int>(N + N + 1, 2 * N));
        int j = 0;
        ll sm = 0;
        rep(i, 2 * N) {
            while (j < 2 * N && sm < X) sm += A[j >= N ? j - N : j], j++;
            table[0][i] = j;
            sm -= A[i >= N ? i - N : i];
        }
        rep(it, 1, LOG) {
            rep(i, N) {
                table[it][i] = table[it - 1][table[it - 1][i]];
            }
        }
        return table;
    };
    ll tv = 0, fv = S[N];
    while (fv - tv > 1) {
        ll m = (tv + fv) / 2;
        auto table = Make(m);
        bool ok = false;
        rep(i, N) {
            int st = i;
            rep(j, LOG) if (K >> j & 1) {
                st = table[j][st];
            }
            if(st <= i + N) ok = true;
        }
        (ok ? tv : fv) = m;
    }
    cout << tv << "\n";
}
int main() {
    std::ios_base::sync_with_stdio(false);
    std::cin.tie(nullptr);
    std::fixed(std::cout).precision(16);
    int T = 1;
    while (T--) run_case();
    return 0;
}