#include <bits/stdc++.h>
#pragma GCC target("avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define all(a) a.begin(),a.end()
#define pb emplace_back
#define eb emplace_back
#define lb(v,k) (lower_bound(all(v),k)-v.begin())
#define ub(v,k) (upper_bound(all(v),k)-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
typedef multiset<ll> S;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=1000000007;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> bool isin(T x,T l,T r){return (l)<=(x)&&(x)<=(r);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void noyes(T b){if(b)out("no");else out("yes");}
template<class T> void NoYes(T b){if(b)out("No");else out("Yes");}
template<class T> void NOYES(T b){if(b)out("NO");else out("YES");}
void outs(ll a,ll b){if(a>=inf-100)out(b);else out(a);}
ll gcd(ll a,ll b){if(b==0)return a;return gcd(b,a%b);}
ll modpow(ll a,ll b){ll res=1;a%=mod;while(b){if(b&1)res=res*a%mod;a=a*a%mod;b>>=1;}return res;}

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll n,k;cin>>n>>k;
    vi v(n*2);
    rep(i,n)cin>>v[i];
    rep(i,n)v[i+n]=v[i];
    ll sum=0;
    rep(i,n)sum+=v[i];
    ll ok=0,ng=sum/k+1;
    while(ng-ok>1){
        ll md=(ok+ng)/2;
        bool able=false;
        if(k<100){
            vi s(k),t(k),a(k);
            rep(tt,n){
                bool b=true;
                if(tt)a[0]-=v[s[0]++];
                rep(i,k){
                    if(chmax(t[i],s[i]))a[i]=0;
                    while(a[i]<md){
                        a[i]+=v[t[i]++];
                        if(i!=k-1)a[i+1]-=v[t[i]-1];
                        if(t[i]>s[0]+n){
                            b=false;break;
                        }
                    }
                    if(!b)break;
                }
                if(b){able=true;break;}
            }
            if(able)ok=md;
            else ng=md;
        }
        else{
            ll r=0;
            rep(i,300)r+=v[i];
            ll res=0;
            rep(i,n-299){
                if(r>=md){
                    res=i;
                    break;
                }
                r-=v[i];r+=v[i+300];
            }
            vi s(k,res),t(k,res),a(k);
            rep(tt,300){
                bool b=true;
                if(tt)a[0]-=v[s[0]++];
                rep(i,k){
                    if(chmax(t[i],s[i]))a[i]=0;
                    while(a[i]<md){
                        a[i]+=v[t[i]++];
                        if(i!=k-1)a[i+1]-=v[t[i]-1];
                        if(t[i]>s[0]+n){
                            b=false;break;
                        }
                    }
                    if(!b)break;
                }
                if(b){able=true;break;}
            }
            if(able)ok=md;
            else ng=md;
        }
    }
    out(ok);
}