#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 chmin(T &a, const T &b){
    if(a > b) {a = b; return true;}
    else return false;
}
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, INF);
    rep(i, N*2){
        if(num[i] == 0) first_id[i] = i;
        auto ite = lower_bound(ALL(sum), sum[i] + m);
        if(ite != sum.end()){
            if(chmax(num[ite - sum.begin()], num[i] + 1)){
                first_id[ite - sum.begin()] = first_id[i];
            }else if(num[ite - sum.begin()] == num[i] + 1){
                chmax(first_id[ite - sum.begin()], first_id[i]);
            }
        }
    }
    rep(i, N * 2){
        if(first_id[i] + N >= i && num[i] >= K) return true;
    }
    return false;
}

int main() {
    cin>>N>>K;
    vec a(N), sum(N * 2 + 1, 0);
    rep(i,N){
        cin>>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 = accumulate(ALL(a), 1LL);
    while(ub - lb > 1){
        ll cen = (ub + lb) / 2;
        (ok(sum, cen) ? lb : ub) = cen;
    }
    cout<<lb<<endl;
}