#include <iostream>
#include <algorithm>
#include <iomanip>
#include <vector>
#include <queue>
#include <set>
#include <map>

using namespace std;
typedef long long ll;

const ll INF = 1e18;

int N, K;
ll A[100005];
ll sum[200005];

ll next_offset[100005][20];
bool used[100005];

void clear_used(){
    for(int i = 0; i < N; i++) used[i] = false;
}

void build(ll m){
    for(int i = 0; i < N; i++){
        auto p = lower_bound(sum, sum+2*N+2, sum[i]+m);
        next_offset[i][0] = (p-(sum+i));
    }
    for(int j = 1; j < 18; j++){
        for(int i = 0; i < N; i++){
            next_offset[i][j] = next_offset[i][j-1]+next_offset[(i+next_offset[i][j-1])%N][j-1];
        }
    }
}

ll cnt(int s){
    ll ans = 0;
    for(int i = 0; i < 18; i++){
        used[s] = true;
        if(K&(1<<i)){
            ans += next_offset[s][i];
            s += next_offset[s][i];
            s %= N;
        }
    }
    return ans;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << setprecision(10) << fixed;
    cin >> N >> K;
    for(int i = 0; i < N; i++){
        cin >> A[i];
        sum[i+1] = sum[i]+A[i];
    }
    for(int i = N; i < 2*N; i++){
        sum[i+1] = sum[i]+A[i%N];
    }
    sum[2*N+1] = INF;
    ll l = 1, r = INF/2;
    while(r-l > 1){
        ll c = (l+r)/2;
        clear_used();
        build(c);
        bool ok = false;
        for(int i = 0; i < N; i++){
            if(!used[i]){
                ll tmp = cnt(i);
                if(tmp <= N) ok = true;
            }
        }
        if(ok) l = c;
        else r = c;
    }
    cout << l << endl;
}