from bisect import bisect_right

N, K, P = map(int, input().split())
A = tuple(int(x) % P for x in input().split())
B = sorted(int(x) % P for x in input().split())


def lower(x):
    ct = 0
    for a in A:
        ct += bisect_right(B, x - a) + bisect_right(B, P + x - a) - bisect_right(B, P - a - 1)
    return ct


l, r = 0, P
while r - l > 1:
    m = (r + l) // 2
    if lower(m) >= K:
        r = m
    else:
        l = m
print(l + 1)