from bisect import *

N, K, P = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
B.sort()
no = -1
yes = P

def check(m):
    cnt = 0
    for a in A:
        cnt += bisect_right(B, m - a)
        cnt += bisect_right(B, P + m - a) - bisect_left(B, P - a)
    return cnt >= K


while yes - no != 1:
    mid = (yes + no)//2
    if check(mid):
        yes = mid
    else:
        no = mid
print(yes)