#include<iostream>

#include<cstdio>

#include<algorithm>

#include<cmath>

#include<cstring>

#include<string>

#include<stack>

#include<queue>

#include<deque>

#include<set>

#include<vector>

#include<map>

#define fst first

#define sc second

#define pb push_back

#define mem(a,b) memset(a,b,sizeof(a))

#define lson l,mid,root<<1

#define rson mid+1,r,root<<1|1

#define lc root<<1

#define rc root<<1|1

#define lowbit(x) ((x)&(-x)) 

using namespace std;

typedef double db;

typedef long double ldb;

typedef long long ll;

typedef unsigned long long ull;

typedef pair<int,int> PI;

typedef pair<ll,ll> PLL;

const db eps = 1e-;

const int mod = 1e9+;

const int maxn = 4e5+;

const int maxm = 4e5+;

const int inf = 0x3f3f3f3f;

const db pi = acos(-1.0);

int n, k;

ll a[maxn];

priority_queue<pair<ll, int> ,vector<pair<ll,int>>, greater<pair<ll,int>> >q;

//priority_queue<pair<ll,int>, vector<pair<ll,int> >, greater<pair<ll,int> > >q;

int main(){

    scanf("%d %d", &n, &k);

    for(int i = ; i <= n; i++){

        scanf("%lld", &a[i]);

    }

    sort(a+,a++n);

    q.push({a[],});

    int cnt = ;

    while(cnt < k){

        auto tmp = q.top();

        q.pop();

        ll ans = tmp.fst;

        int id = tmp.sc;

        if(id < n){

            q.push({ans+a[id+],id+});

            q.push({ans-a[id]+a[id+], id+});

        }

        cnt++;

        if(cnt == k){

            printf("%lld\n", ans);

            break;

        }

    }

    return ;

}