import sys
def main():
    input = sys.stdin.readline
    N, K, P = map(int, input().split())
    *A, = map(int, input().split())
    *B, = map(int, input().split())
    A.sort()
    B.sort()
    C = [0] * (P)
    for b in B:
        C[b] += 1
    for i in range(1, P):
        C[i] += C[i - 1]

    # x以下の要素の数
    def f(x):
        res = 0
        for a in A:
            # Ai+Bj <= x
            if x - a >= 0:
                res += C[x - a]
            # P <= Ai+Bi <= P+x
            res += C[min(P - 1, P + x - a)] - C[P - a - 1]
        return res

    l = -1
    r = P - 1
    while r - l > 1:
        m = (l + r) // 2
        if f(m) < K: l = m
        else: r = m
    print(r)

if __name__ == '__main__':
    main()