N,K,P = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))


C = P * 2
S = [0] * (C+1)
for b in B:
    S[b] += 1
for i in range(1,C+1):
    S[i] += S[i-1]

def calc(x):
    ans = 0
    for a in A:
        if a <= x:
            ans += S[x-a]
        ans += S[x+P-a] - S[P-a-1]
    return ans >= K
    
end = P-1
start = -1
while end - start > 1:
    mid = end + start >> 1
    if calc(mid):
        end = mid
    else:
        start = mid
print(end)