#include <iostream>
#include <cstdio>
#include <cmath>
#include <ctime>
#include <cstdlib>
#include <cassert>
#include <vector>
#include <list>
#include <stack>
#include <queue>
#include <deque>
#include <map>
#include <set>
#include <bitset>
#include <string>
#include <algorithm>
#include <utility>
#define llint long long
#define inf 1e18
#define rep(x, s, t) for(llint (x) = (s); (x) < (t); (x)++)
#define Rep(x, s, t) for(llint (x) = (s); (x) <= (t); (x)++)
#define chmin(x, y) (x) = min((x), (y))
#define chmax(x, y) (x) = max((x), (y))
#define mod 1000000007

using namespace std;
typedef pair<llint, llint> P;

llint n, k;
llint a[300005], sum[300005];
llint succ[100005][17];

bool check(llint d)
{
	if(d > sum[n]) return false;
	
	llint r = -1;
	for(int i = 0; i < n; i++){
		while(r < i || sum[r]-sum[i] < d) r++;
		succ[i][0] = r-i;//lower_bound(sum, sum+3*n, sum[i] + d) - (sum+i);
	}
	for(int i = 1; i < 17; i++){
		for(int j = 0; j < n; j++){
			succ[j][i] = succ[j][i-1] + succ[(j+succ[j][i-1])%n][i-1];
		}
	}
	
	for(int i = 0; i < n; i++){
		llint v = i, s = 0;
		for(int j = 16; j >= 0; j--){
			if(k & (1<<j)){
				s += succ[v][j];
				if(s > n) goto end;
				v += succ[v][j], v %= n;
			}
		}
		return true;
		end:;
	}
	return false;
}

int main(void)
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	
	cin >> n >> k;
	for(int i = 0; i < n; i++) cin >> a[i];
	for(int i = n; i < 3*n; i++) a[i] = a[i%n];
	
	llint s = 0;
	for(int i = 0; i < 3*n; i++){
		sum[i] = s;
		s += a[i];
	}
	
	llint ub = 2e14, lb = 0, mid;
	while(ub-lb>1){
		mid = (ub+lb)/2;
		if(check(mid)) lb = mid;
		else ub = mid;
	}
	cout << lb << endl;
	
	return 0;
}