//#define _GLIBCXX_DEBUG

#include<bits/stdc++.h>
using namespace std;

#define endl '\n'
#define lfs cout<<fixed<<setprecision(10)
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()
#define spa << " " <<
#define fi first
#define se second
#define MP make_pair
#define MT make_tuple
#define PB push_back
#define EB emplace_back
#define rep(i,n,m) for(ll i = (n); i < (ll)(m); i++)
#define rrep(i,n,m) for(ll i = (ll)(m) - 1; i >= (ll)(n); i--)
using ll = long long;
using ld = long double;
const ll MOD1 = 1e9+7;
const ll MOD9 = 998244353;
const ll INF = 1e18;
using P = pair<ll, ll>;
template<typename T1, typename T2>bool chmin(T1 &a,T2 b){if(a>b){a=b;return true;}else return false;}
template<typename T1, typename T2>bool chmax(T1 &a,T2 b){if(a<b){a=b;return true;}else return false;}
ll median(ll a,ll b, ll c){return a+b+c-max({a,b,c})-min({a,b,c});}
void ans1(bool x){if(x) cout<<"Yes"<<endl;else cout<<"No"<<endl;}
void ans2(bool x){if(x) cout<<"YES"<<endl;else cout<<"NO"<<endl;}
void ans3(bool x){if(x) cout<<"Yay!"<<endl;else cout<<":("<<endl;}
template<typename T1,typename T2>void ans(bool x,T1 y,T2 z){if(x)cout<<y<<endl;else cout<<z<<endl;}  
template<typename T>void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++){cout<<v[i][0];for(ll j=1;j<w;j++)cout spa v[i][j];cout<<endl;}};
void debug(vector<string>&v,ll h,ll w){for(ll i=0;i<h;i++){for(ll j=0;j<w;j++)cout<<v[i][j];cout<<endl;}};
template<typename T>void debug(vector<T>&v,ll n){if(n!=0)cout<<v[0];for(ll i=1;i<n;i++)cout spa v[i];cout<<endl;};
template<typename T>vector<vector<T>>vec(ll x, ll y, T w){vector<vector<T>>v(x,vector<T>(y,w));return v;}
ll gcd(ll x,ll y){ll r;while(y!=0&&(r=x%y)!=0){x=y;y=r;}return y==0?x:y;}
vector<ll>dx={1,-1,0,0,1,1,-1,-1};vector<ll>dy={0,0,1,-1,1,-1,1,-1};
template<typename T>vector<T> make_v(size_t a,T b){return vector<T>(a,b);}
template<typename... Ts>auto make_v(size_t a,Ts... ts){return vector<decltype(make_v(ts...))>(a,make_v(ts...));}
template<typename T1, typename T2>ostream &operator<<(ostream &os, const pair<T1, T2>&p){return os << p.first << " " << p.second;}
template<typename T>ostream &operator<<(ostream &os, const vector<T> &v){for(auto &z:v)os << z << " ";cout<<"|"; return os;}
//mt19937 mt(chrono::steady_clock::now().time_since_epoch().count());
struct Permutation{
  ll sz;
  vector<ll>perm;
  Permutation(ll sz):sz(sz){
    perm.assign(sz,0);
    iota(perm.begin(),perm.end(),0);
  }
  Permutation(vector<ll>&v):sz(v.size()){
    perm=v;
  }
  ll &operator[](const ll idx){
    return perm[idx];
  }
  ll operator[](ll idx)const {
    return perm[idx];
  }
  //順序に注意！ 
  Permutation operator*(const Permutation &p){
    Permutation ret(sz);
    for(ll i=0;i<sz;i++)ret[i]=(*this)[p[i]];
    return ret;
  }
  Permutation &operator*=(const Permutation &p){
    *this = *this * p;
    return *this;
  }
  Permutation &operator^=(ll k){
    Permutation ret(sz);
    Permutation tmp = *this;
    while(k){
      if(k&1)ret *= tmp;
      tmp *= tmp;
      k>>=1;
    }
    *this = ret;
    return *this;
  }
  Permutation inv(){
    Permutation ret(sz);
    for(ll i=0;i<sz;i++)ret[(*this)[i]]=i;
    return ret;
  }
};
int main(){
  cin.tie(nullptr);
  ios_base::sync_with_stdio(false);
  ll res=0,buf=0;
  bool judge = true;
  ll n,k;cin>>n>>k;
  vector<ll>a(n);
  rep(i,0,n)cin>>a[i];
  vector<ll>b(2*n+1);
  rep(i,0,2*n)b[i+1]=b[i]+a[i%n];
  ll ok=0,ng=INF;
  while(abs(ng-ok)>=2){
    ll mid=(ng+ok)/2;
    vector<ll>p(2*n+2,2*n+1);
    rep(i,0,2*n){
      p[i]=lower_bound(ALL(b),b[i]+mid)-b.begin();
    }
    Permutation q(p);
    //debug(p,2*n+1);
    q^=k;
    ll dif=INF;
    rep(i,0,n)chmin(dif,q[i]-i);
    if(dif<=n)ok=mid;
    else ng=mid;
  }
  cout<<ok<<endl;
  return 0;
}