import numpy as np
N, K, P = map(int, input().split())
A = list(map(int, input().split()))
B = list(map(int, input().split()))

s = [0]*(10**7+1)
t = [0]*(10**7+1)

fft_len = 2**24
for a in A:
    s[a] += 1
for b in B:
    t[b] += 1

s = np.array(s, dtype=np.int32)
t = np.array(t, dtype=np.int32)

Fs = np.fft.rfft(s, fft_len)
Ft = np.fft.rfft(t, fft_len)
Fst = Fs*Ft
st = np.fft.irfft(Fst, fft_len)
st = list(np.rint(st))

ans = [0]*P

for i, v in enumerate(st):
    ans[i % P] += v

cnt = 0
for i in range(P):
    cnt += int(ans[i])
    if cnt >= K:
        print(i)
        break