import sys
from collections import defaultdict, Counter, deque
from itertools import permutations, combinations, product, combinations_with_replacement, groupby, accumulate
import operator
from math import sqrt, gcd, factorial
# from math import isqrt, prod,comb  # python3.8用(notpypy)
#from bisect import bisect_left,bisect_right
#from functools import lru_cache,reduce
#from heapq import heappush,heappop,heapify,heappushpop,heapreplace
#import numpy as np
#import networkx as nx
#from networkx.utils import UnionFind
#from numba import njit, b1, i1, i4, i8, f8
#from scipy.sparse import csr_matrix
#from scipy.sparse.csgraph import shortest_path, floyd_warshall, dijkstra, bellman_ford, johnson, NegativeCycleError
# numba例 @njit(i1(i4[:], i8[:, :]),cache=True) 引数i4配列、i8 2次元配列,戻り値i1
def input(): return sys.stdin.readline().rstrip()
def divceil(n, k): return 1+(n-1)//k  # n/kの切り上げを返す
def yn(hantei, yes='Yes', no='No'): print(yes if hantei else no)


def main():
    mod = 10**9+7
    mod2 = 998244353
    n, k, p = map(int, input().split())
    A = sorted(list(map(lambda x: int(x) % p, input().split())))
    A = [-100]+A+list(map(lambda x: x+p, A))
    B = sorted(list(map(lambda x: int(x) % p, input().split())))

    def is_ok(arg):
        # 条件を満たすかどうか？問題ごとに定義
        l, r = 2*n,2*n
        check = 0
        for BB in B:
            while A[l]+BB >= p:
                l -= 1
            while A[r]+BB >= p+arg+1:
                r -= 1
            check += r-l
        return check >= k
    
    def meguru_bisect(ng, ok):
        '''
        初期値のng,okを受け取り,is_okを満たす最小(最大)のokを返す
        まずis_okを定義すべし
        ng ok は  とり得る最小の値-1 とり得る最大の値+1
        最大最小が逆の場合はよしなにひっくり返す
        '''
        while (abs(ok - ng) > 1):
            mid = (ok + ng) // 2
            if is_ok(mid):
                ok = mid
            else:
                ng = mid
        return ok
    print(meguru_bisect(-1,p))


if __name__ == '__main__':
    main()