#include <bits/stdc++.h>
//#include <chrono>
#pragma GCC optimize("Ofast")
using namespace std;
#define reps(i,s,n) for(int i = s; i < n; i++)
#define rep(i,n) reps(i,0,n)
#define Rreps(i,n,e) for(int i = n - 1; i >= e; --i)
#define Rrep(i,n) Rreps(i,n,0)
#define ALL(a) a.begin(), a.end()
#define fi first
#define se second
typedef long long ll;
typedef vector<ll> vec;
typedef vector<vec> mat;

ll N,M,H,W,Q,K,A,B;
string S;
typedef pair<ll, ll> P;
const ll INF = (1LL<<60);

template<class T> bool chmax(T &a, const T &b){
    if(a < b) {a = b; return true;}
    else return false;
}

bool ok(vec &sum, ll m){
    vec num(N*2 + 1, 0), first_id(N*2 + 1);
    rep(i, N * 2 + 1) first_id[i] = i;
    int l(0), r(0);
    while(r <= N * 2 && l <= N){
        ll d = sum[r] - sum[l];
        if(d >= m) {
            if (chmax(num[r], num[l] + 1)) {
                first_id[r] = first_id[l];
            } else if (num[r] == num[l] + 1) {
                chmax(first_id[r], first_id[l]);
            }
            if(first_id[r] + N >= r && num[r] >= K) return true;
        }
        d >= m ? ++l : ++r;
    }
    return false;
}

int main() {
    cin>>N>>K;
    vec a(N), sum(N * 2 + 1, 0);
    rep(i,N){
        scanf("%lld", &a[i]);
        sum[i + 1] = a[i] + sum[i];
    }
    reps(i, N, N * 2) sum[i + 1] = sum[i] + a[i - N];
    ll lb = 1, ub = (sum[N] - 1) / K + 2;
    while(ub - lb > 1){
        ll cen = (ub + lb) / 2;
        (ok(sum, cen) ? lb : ub) = cen;
    }
    cout<<lb<<endl;
}