import bisect
from functools import cache
N,K,P = list(map(int,input().split()))
A = list(map(int,input().split()))
B = list(map(int,input().split()))
A.sort()
B.sort()

memo_l = [-1 for _ in range(P+1)]
def memo_bisect_left(p):
    if(p >= P):return N
    if(p < 0):return 0
    if(memo_l[p] != -1):return memo_l[p]
    memo_l[p] = bisect.bisect_left(B,p)
    return memo_l[p]

memo_r = [-1 for _ in range(P)]
def memo_bisect_right(p):
    if(p >= P):return N
    if(p < 0):return 0
    if(memo_r[p] != -1):return memo_r[p]
    memo_r[p] = bisect.bisect_right(B,p)
    return memo_r[p]

def check(n):
    count = 0
    for i in A:
        left = memo_bisect_left(P-i)
        right = memo_bisect_right(n+P-i)
        count += right - left

        right2 = memo_bisect_right(n-i)
        count += right2
    return count >= K

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