import sys
import bisect
input = sys.stdin.buffer.readline


def solve(val):
    cnt = 0
    for va in a:
        if va <= val:
            l = val - va
            r = p - va - 1
            cnt += bisect.bisect_right(b, l)
            cnt += n - bisect.bisect_right(b, r)
        else:
            l = p - va
            r = l + val + 1
            cnt += bisect.bisect_left(b, r) - bisect.bisect_left(b, l)
    return cnt

n, k, p = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))

b = sorted(b)
ok = p
ng = -1
while abs(ok - ng) > 1:
    mid = (ok + ng) // 2
    if solve(mid) >= k:
        ok = mid
    else:
        ng = mid
print(ok)