#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<complex>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<utility>
#include<tuple>
#include<cassert>
using namespace std;
typedef long long ll;
typedef unsigned int ui;
const ll mod = 1000000007;
const ll INF = (ll)1000000007 * 1000000007;
typedef pair<int, int> P;
#define stop char nyaa;cin>>nyaa;
#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define Per(i,sta,n) for(int i=n-1;i>=sta;i--)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
typedef long double ld;
const ld eps = 1e-8;
const ld pi = acos(-1.0);
typedef pair<ll, ll> LP;
int dx[4]={1,-1,0,0};
int dy[4]={0,0,1,-1};

int n,k;
ll a[100010];
vector<ll> S;

bool check(ll x){
    vector<vector<int>> table(2*n+2,vector<int>(18,0));
    int r=0;
    rep(i,2*n+1){
        while(S[r]-S[i]<x){
            r++;
        }
        table[i][0]=r;
        //cout << i << " " << table[i][0] << endl;
    }
    rep(j,18){
        table[2*n+1][j]=2*n+1;
    }
    rep(j,17){
        rep(i,2*n+1){
            table[i][j+1]=table[table[i][j]][j];
        }
    }
    rep(i,n){
        int pos=i;
        rep(j,17){
            if(k&(1 << j)) pos=table[pos][j];
        }
        if(pos<=i+n){
            return true;
        }
    }
    return false;
}

void solve(){
    cin >> n >> k;
    rep(i,n) cin >> a[i];
    S.resize(2*n+2);
    rep(i,n){
        S[i+1]=S[i]+a[i];
    }
    rep(i,n){
        S[i+n+1]=S[i+n]+a[i];
    }
    S[2*n+1]=INF;
    ll l=0,r=S[n]/k+3;
    while(r-l>1){
        ll mid=(l+r)/2;
        if(check(mid)) l=mid;
        else r=mid;
    }
    cout << l << endl;
    return;
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout << fixed << setprecision(50);
    solve();
}