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-(x[l-1]-x[r])
        else:
            res+=x[r]-x[l-1]
    return res
n,k,p=map(int,input().split())
x=[0]*(p+1)
a=list(map(int,input().split()))
for i in list(map(int,input().split())):
	x[i+1]+=1
for i in range(1,len(x)):
	x[i]+=x[i-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)