def aa(s):
    res=0;d=1
    while s:
        if s&d:
            res+=fen[s];s-=d
        d<<=1
    return res
def bb(m):
    global p,n
    res=0
    for i in a:
        l,r=(-i)%p+1,(m-i)%p+1
        if l>r:
            res+=n-(aa(l-1)-aa(r))
        else:
            res+=aa(r)-aa(l-1)
    return res
n,k,p=map(int,input().split())
fen=[0]*(p+1)
a=list(map(int,input().split()))
b=list(map(int,input().split()))
for i in b:
    s=i+1;d=1
    while s<=p:
        if s&d:
            fen[s]+=1
            s+=d
        d<<=1
q,w=-1,p-1
while w-q>1:
    m=(q+w)//2
    if bb(m)<k:
        q=m
    else:
        w=m
print(w)