import sys
# sys.setrecursionlimit(10 ** 9)  # Codeforcesでは350000程度に
def input(): return sys.stdin.readline().strip()


n, k, p = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

AN = [0] * p
for i in range(n):
    AN[A[i]] += 1
AN = [0] + AN + AN
for i in range(len(AN)-1):
    AN[i+1] += AN[i]
# print(AN)

ok = p
ng = -1
while abs(ok - ng) > 1:
    mi = (ok + ng) // 2
    cnt = 0
    for i in range(n):
        l = p - B[i] if B[i] != 0 else 0
        r = l + mi
        # print("l,r", l, r)
        cnt += AN[r+1] - AN[l]
    # print(mi, cnt)
    if cnt >= k:
        ok = mi
    else:
        ng = mi
print(ok)