#include <bits/stdc++.h>


#define MAX 201000

int main()
{
    int count, k;

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

    int *nums = new int[count];
    int *nums2 = new int[count];
    int count2;

    for(int i = 0; i < count; i++)
    {
        scanf("%d", &nums[i]);
    }

    for(int maxbit = 30; maxbit >= 0; maxbit--)
    {
        count2 = 0;
        int mask = 1 << maxbit;
        for(int i = 0; i < count; i++)
        {
            if((nums[i] & mask) > 0)
                nums2[count2++] = nums[i];
        }

        if(count2 >= k)
        {
            int *h = nums;
            nums = nums2;
            nums2 = h;
            int a = count;
            count = count2;
            count2 = a;
        }

        if(count == k)
            break;
    }

    

    int result = ~0;
    for(int i = 0; i < count; i++)
        result &= nums[i];

    printf("%d", result);

    delete[] nums;
    delete[] nums2;

    return 0;
}