/* -*- coding: utf-8 -*-
 *
 * 1211.cc:  No.1211 円環はお断り - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;
const int MAX_N2 = MAX_N * 2;
const int BN = 18;
const int INF = 1 << 30;

/* typedef */

typedef long long ll;

/* global variables */

int as[MAX_N2], ps[MAX_N2 + 1][BN];

/* subroutines */

bool check(int n, int k, int bn, ll m) {
  int n2 = n * 2;
  ll sum = 0;
  for (int i = 0, j = 0; i < n2; i++) {
    while (j < n2 && sum < m) sum += as[j++];
    ps[i][0] = (sum >= m) ? j : INF;
    sum -= as[i];
  }
  ps[n2][0] = INF;

  for (int b = 0; b + 1 < bn; b++)
    for (int i = 0; i <= n2; i++)
      ps[i][b + 1] = (ps[i][b] < INF) ? ps[ps[i][b]][b] : INF;

  for (int i = 0; i < n; i++) {
    int j = i;
    for (int b = bn - 1; b >= 0 && j < INF; b--)
      if ((k >> b) & 1) j = ps[j][b];
    if (j - i <= n) return true;
  }

  return false;
}

/* main */

int main() {
  int n, k;
  scanf("%d%d", &n, &k);
  int n2 = n * 2;

  ll asum = 0;
  for (int i = 0; i < n; i++) {
    scanf("%d", as + i), as[n + i] = as[i];
    asum += as[i];
  }

  int bn = 0;
  for (int bi = 1; bi <= n2; bn++, bi <<= 1);
  //printf("bn=%d\n", bn);

  ll m0 = 1, m1 = asum + 1;
  while (m0 + 1 < m1) {
    ll m = (m0 + m1) / 2;
    if (check(n, k, bn, m)) m0 = m;
    else m1 = m;
  }

  printf("%lld\n", m0);
  return 0;
}