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())

B_counter = [0] * P
for b in B:
    B_counter[b] += 1
for i in range(1, P):
    B_counter[i] += B_counter[i - 1]


def lower(x):
    ct = 0
    for a in A:
        i1 = x - a
        if i1 < 0: i1 = 0
        i2 = P + x - a
        if i2 >= P: i2 = P - 1
        
        ct += B_counter[i1] + B_counter[i2] - B_counter[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)