K, N = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))


def calc():
    res = -10**18
    for i in range(1, K+1):
        res = max(res, min(A[-i], B[-i]))
    return res


for _ in range(K):
    A.append(calc())


if N <= len(A)-1:
    print(A[N])
    quit()


from heapq import heappop, heappush

def check(x):
    AA = [a>=x for a in A]
    T = []
    for i, b in enumerate(B):
        if b >= x:
            T.append(K - i)
    
    if len(T) == 0:
        return False
    
    t0 = T[0]
    Min = [-1] * t0
    hq = []
    for i in range(K, 2*K):
        if AA[i]:
            heappush(hq, (i, i%t0))
    while hq:
        i, pos = heappop(hq)
        if Min[pos] != -1:
            continue
        Min[pos] = i
        for t in T:
            ii = (i+t) % t0
            if Min[ii] == -1:
                heappush(hq, (i+t, ii))
    return 0 <= Min[N%t0] <= N


S = sorted(set(A + B))
if check(S[-1]):
    print(S[-1])
    quit()

ok = 0
ng = len(S) - 1
while ok+1 < ng:
    mid = (ok + ng) // 2
    if check(S[mid]):
        ok = mid
    else:
        ng = mid

print(S[ok])