n, k, p = map(int, input().split())
a = list(map(int, input().split()))
b = list(map(int, input().split()))
cnt = [0] * (p + 1)
for i in a:
    cnt[i + 1] += 1
for i in range(p):
    cnt[i + 1] += cnt[i]


def count(l, r):
    return cnt[r] - cnt[l]


def calc(m):
    res = 0
    for i in b:
        res += count(0, max(m - i, 0)) + count(p - i, min(p, p + m - i))
    return res


ng, ok = p, -1
while ng - ok > 1:
    m = (ok + ng) // 2
    if calc(m) < k:
        ok = m
    else:
        ng = m
print(ok)