N,K,P = map(int,input().split())
A = list(map(int,input().split()))
B = list(map(int,input().split()))
imos = [0]*(P+1)
for i in range(N):
    imos[B[i]+1] += 1
for i in range(P):
    imos[i+1] += imos[i]
left = -1
right = P-1
while left+1 < right:
    mid = (left+right)//2
    cnt = 0
    for i in range(N):
        l = -A[i]
        r = mid-A[i]
        if r < 0:
            cnt += imos[r+P+1]-imos[l+P]
        else:
            cnt += imos[r+1]+imos[P]-imos[l+P]
    if cnt >= K:
        right = mid
    else:
        left = mid
print(right)