#include<cstdio>
#include<algorithm>
using namespace std;
long long a[500001],b[500001];
int main()
{
        int t,ti;
        //freopen("input.in","r",stdin);
        scanf("%d",&t);
        for (ti=1;ti<=t;++ti)
        {
        int m,i,j;
        long long l1=0,l2=0;
        scanf("%d",&m);
        for (i=0;i<m;++i)
                {
                scanf("%lld",&a[i]);
                l1+=a[i];
                }
        for (i=0;i<m;++i)
                {
                scanf("%lld",&b[i]);
                l2+=b[i];
                }
        if (l1<l2) a[0]+=(l2-l1);
                else if (l1>l2) b[0]+=(l1-l2);
        long long ans=0;
        for (i=1;i<=m-1;++i)
                {
                if (not (min(a[i],b[m-i])>=1)) continue;
                a[i]-=1,b[m-i]-=1;
                long long s1=1;
                for (j=0;j<=m-1;++j)
                        s1+=min(a[j],b[m-1-j]);
                ans=max(ans,s1);
                a[i]+=1,b[m-i]+=1;
                }
        printf("%lld\n",ans);
        }
        return 0;
}