#include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<array>
#include<map>
#include<iomanip>
#include<assert.h>
#include<list>
#include<bitset>
#include<stack>
#include<memory>
#include<numeric>
using namespace std;
using namespace std::chrono;
typedef long long int llint;
typedef long double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
#define REP(i, n) for(int i = 0;i < (n);i++)
/*cout<<fixed<<setprecision(20);cin.tie(0);ios::sync_with_stdio(false);*/
const llint mod=1000000007;
const llint inf=2.19e15+1;
const long double pai=3.141592653589793238462643383279502884197;
const long double eps=1e-10;
template <class T,class U>bool chmin(T& a,U b){if(a>b){a=b;return true;}return false;}
template <class T,class U>bool chmax(T& a,U b){if(a<b){a=b;return true;}return false;}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){if(a==0){return b;}return a/gcd(a,b)*b;}
template<class T> void SO(T& ve){sort(ve.begin(),ve.end());}
template<class T> void REV(T& ve){reverse(ve.begin(),ve.end());}
template<class T>llint LBI(const vector<T>&ar,T in){return lower_bound(ar.begin(),ar.end(),in)-ar.begin();}
template<class T>llint UBI(const vector<T>&ar,T in){return upper_bound(ar.begin(),ar.end(),in)-ar.begin();}


bool solve(int n,int K,llint S,const vector<llint>&wa){
	static int go[17][200101];
	int h,i,j;
	for(i=0;i<=n+n;i++){go[0][i]=LBI(wa,wa[i]+S);}
	go[0][n+n+1]=n+n+1;
	for(h=1;h<17;h++){
		for(i=0;i<=n+n+1;i++){go[h][i]=go[h-1][go[h-1][i]];}
	}
	for(i=0;i<n;i++){
		int gen=i;
		for(h=0;h<17;h++){
			if(K&(1<<h)){gen=go[h][gen];}
		}
		if(gen<=i+n){return true;}
	}
	return false;
}

int main(void){
	int n,K,i;cin>>n>>K;
	llint bmax=inf,bmin=0;
	vector<llint>wa(n+n+1);
	for(i=1;i<=n;i++){
		llint A;cin>>A;
		wa[i]=wa[i-1]+A;
	}
	for(i=n+1;i<=n+n;i++){wa[i]=wa[i-n]+wa[n];}
	//for(i=0;i<n;i++){cerr<<wa[i]<<endl;}
	while(bmax-bmin>1){
		llint bgen=(bmax+bmin)/2;
		if(solve(n,K,bgen,wa)){bmin=bgen;}
		else{bmax=bgen;}
	}
	cout<<bmin<<endl;
	return 0;
}
/*
a b c
a abc c
*/