#include<stdio.h>
#include<iostream>
#include<string.h>
#include<string>
#define VOL 205
#define FOR(i, j, k) for(int i=j; i<k; i++)
using namespace std;
typedef long long LL;
int num;
string ccc[105];
int minlen ;
int movelen, k;
int mid_len, n;

int test(string str1)
{
   string str2(str1.rbegin(), str1.rend());  
    for(int i=1; i<=num; i++)
    {
		if(ccc[i].find(str1) == -1)
        {
        	if(ccc[i].find(str2) == -1 )
            	return 0;
        }
    }
    return 1;
}

void solve()
{
    for(int i=0; i<mid_len; i++)
    {
        for(int j=0; j<=mid_len-movelen; j++)
        {
            string mid_string1;
            mid_string1 = ccc[k].substr(j, movelen);
            if(test(mid_string1))
            {
                cout<<movelen<<endl;
                return;
            }
        }
        movelen--;
    }
    cout<<"0"<<endl;
    return;
}

int main()
{
    //freopen("D:\\CPPProgram\\ACM\\in.txt", "r", stdin);
    cin>>n;
    while (n--)
    {
        minlen = 110;
        cin>>num;
		for (int i=1; i<=num; i++)
        {
            cin>>ccc[i];
            mid_len= ccc[i].length();
            if(mid_len<minlen)
            {
                k = i;
                minlen = mid_len;
                movelen = minlen;
            }
        }
        solve();
    }
    return 0;
}