from bisect import *
N, K, P = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
A.sort()
A += [i + P for i in A]

def check(c):
    tmp = 0
    for b in B:
        x = bisect_left(A, P - b)
        y = bisect(A, P - b + c)
        tmp += y - x
    return tmp >= K

lb = 0
ub = P
while ub - lb > 1:
    mid = (ub + lb) // 2
    if check(mid):
        ub = mid
    else:
        lb = mid
print(ub)