#include<iostream>
#include<algorithm>
#include<string>
using namespace std;

const int INF = 0x3f3f3f3f;

string str[110];

int main()
{
	int kase,n;
	int minl=INF;
	int minpos;
	cin >> kase;
	
	while(kase--)
	{
		minl = INF;
		cin >> n;
		for(int i = 0; i < n; i++)
		{
			cin >> str[i];
			if(str[i].length() < minl)
			{
				minl = str[i].length();
				minpos = i;
			}
		}
		string key = str[minpos];
		string tem, rev;

		for(int i = minl; i >= 1; i--)  //取字符串长度
		{
			for(int j = 0; j + i -1 < minl; j++)
			{
				tem = string( key.begin() + j, key.begin() + j + i  );
				rev = string( tem.rbegin(), tem.rend() );

				bool flag = true;
				for(int k = 0; k < n; k++)
				{
					if(str[k].find( tem ) == string::npos && str[k].find( rev ) == string::npos)
					{
						flag = false;
						break;
					}
				}

				if(flag)
				{
					printf( "%d\n", i );
					goto here;
				}
			}
		}
		printf( "0\n" );
here:;
	}
	return 0;
}