#include <cstdio>
#include <set>
#include <list>


inline bool isNthBitOne(unsigned x, unsigned n) {
    return (x >> n) % 2 == 1;
}

int main() {
    const unsigned listArraySize = 30;
    std::multiset<unsigned> bits[listArraySize];
    std::list<unsigned> temp;
    unsigned n, k, musician, m, w, count;
    int i, j;

    scanf("%d %d", &n, &k);
    for(i = 0; i < n; ++i) {
        scanf("%d", &musician);
        w = 0;
        m = musician;
        while(musician > 0) {
            if(musician % 2 == 1) {
                bits[w].insert(m);
            }
            musician /= 2;
            ++w;
        }
    }

    bool success = false;
    for(i = listArraySize - 1; i >=0; --i) {
        if(bits[i].size() >= k) {
            break;
        }
    }

    for(j = i - 1; j >= 0 && bits[i].size() > k; --j) {
        count = 0;
        for(unsigned x : bits[i]) {
            if(isNthBitOne(x, j)) {
                ++count;
            } else {
                temp.push_back(x);
            }
        }
        if(bits[i].size() > k && count >= k) {
            for(unsigned x : temp) {
                bits[i].erase(x);
                if(bits[i].size() == k) {
                    break;
                }
            }
        }
        temp.clear();
    }

    unsigned res = *bits[i].begin();
    for(unsigned x : bits[i]) {
        res &= x;
    }

    printf("%u\n", res);

    return 0;
}