from bisect import bisect_left, bisect_right

N, K, P = map(int, input().split())
As = list(map(int, input().split()))
Bs = sorted(map(int, input().split()))

def isok(m):
    cnt = 0
    for A in As:
        cnt += bisect_right(Bs, m - A) # - bisect_left(Bs, - A)
        cnt += bisect_right(Bs, m - A + P) - bisect_left(Bs, - A + P)
    return cnt < K

ok = -1
ng = P
while ng - ok > 1:
    mid = (ok + ng) // 2
    if isok(mid):
        ok = mid
    else:
        ng = mid

print(ok + 1)