import fileinput
def D(a):print(a)
def S(s,I):return int(s.split(" ")[I])
def main():
    z=0
    N=0
    K=0
    A=0
    O=0
    for l in fileinput.input():
        z+=1
        if(z<2):
            N=S(l,0)
            K=S(l,1)
        else:A=map(int,l.split(" "))
    for i in xrange(32,-1,-1):
        T=0
        for j in range(N):
            if((A[j]&(1<<i)) != 0):
                T+=1
        if(T>=K):
            I=0
            O|=1<<i
            for j in range(N):
                if((A[j]&(1<<i))!=0):
                    A[I]=A[j];
                    I+=1
            N=I
    D(O)
main()