mod = 1000000007
eps = 10**-9


def main():
    import sys
    from bisect import bisect_left
    input = sys.stdin.readline

    N, K, P = map(int, input().split())
    A = list(map(int, input().split()))
    B = list(map(int, input().split()))

    A = [a % P for a in A]
    B = [b % P for b in B]
    A.sort()
    B.sort()

    ok = P-1
    ng = -1
    mid = (ok + ng) // 2
    while ok - ng > 1:
        cnt = 0
        for a in A:
            cnt += bisect_left(B, mid - a + 1)
            cnt += bisect_left(B, P + mid - a + 1) - bisect_left(B, P - a)
        if cnt >= K:
            ok = mid
        else:
            ng = mid
        mid = (ok + ng) // 2
    print(ok)


if __name__ == '__main__':
    main()