#4_ACPC11B.txt

#include<stdio.h>

int main()

{

    int t;

    scanf("%d",&t);

    while(t--)

    {

        int n;

        scanf("%d",&n);

        int a[n],i;

        for(i=0;i<n;i++)

            scanf("%d",&a[i]);

        int m;

        scanf("%d",&m);

        int b[m];

        for(i=0;i<m;i++)

            scanf("%d",&b[i]);

        int diff=1000000,s,j;

        for(i=0;i<n;i++)

        {

            for(j=0;j<m;j++)

            {

                if(a[i]>b[j])

                    s= a[i]-b[j];

                else

                    s= b[j]-a[i];

                if(s<diff)

                    diff=s;





            }

        }

        printf("%d\n",diff);

    }

    return 0;

}