#include <stdio.h>

#define PATRAT 3000000
#define NMAX 50000

long a[NMAX];
long n, k;
int count[PATRAT];

void read()
{
long i;

scanf("%ld %ld\n", &n, &k);

for(i = 0; i < n; ++i)
	scanf("%ld\n", &a[i]);
}


void make_sume()
{
long i, j;

for(i = 0; i < n; ++i)
	for(j = 0; j < n; ++j)
		++count[ a[i] + a[j] ];

}

void find()
{
long i, curent;

for( i = curent = 0; i < PATRAT; ++i)
	{
		curent += count[i];

		if(curent >= k)
			{
				printf("%ld\n", i);

				i = PATRAT+1;
			}
	}
}


int main()
{
freopen("sume.in", "r", stdin);
freopen("sume.out", "w", stdout);


read();


make_sume();


find();


fclose(stdin);
fclose(stdout);

return 0;
}