Untitled

# cook your dish here
import statistics as sts
for q in range(int(input())):
    n=int(input())
    a=list(map(int,input().split()))
    b=list(map(int,input().split()))
    a.sort()
    b.sort()
    if (n==2):
        print(min(abs(a[0]-b[0]), abs(a[1]-b[0])))
        continue
    se=[]
    for i in range(n):
        for j in range(n-1):
            m=abs(b[j]-a[i])
            se.append(m)
    d=sts.multimode(se)
    print((d))