mod = 1000000007
eps = 10**-9


def main():
    import sys
    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()
    A.reverse()

    ok = P-1
    ng = -1
    mid = (ok + ng) // 2
    while ok - ng > 1:
        cnt = 0
        i0 = i1 = i2 = 0
        for i in range(N):
            if B[i] <= mid - A[0]:
                i0 = i+1
            if B[i] < P - A[0]:
                i1 = i+1
            if B[i] <= mid + P - A[0]:
                i2 = i+1
        for a in A:
            while True:
                flg = 0
                if i0 < N:
                    if B[i0] <= mid - a:
                        i0 += 1
                        flg = 1
                if i1 < N:
                    if B[i1] < P - a:
                        i1 += 1
                        flg = 1
                if i2 < N:
                    if B[i2] <= mid + P - a:
                        i2 += 1
                        flg = 1
                if not flg:
                    break
            #print(i0, i1, i2)
            cnt += i0 + i2 - i1
        if cnt >= K:
            ok = mid
        else:
            ng = mid
        #print(ok, ng)
        mid = (ok + ng) // 2
    print(ok)


if __name__ == '__main__':
    main()