1226

/*
	字符串处理，
	可以用trie,后缀数组,暴力等算法实现
	暂时用trie tree实现
*/

// include file
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <ctime>

#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <bitset>

#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <list>
#include <functional>

using namespace std;

// typedef
typedef long long LL;
typedef unsigned long long ULL;

// 
#define read freopen("in.txt","r",stdin)
#define write freopen("out.txt","w",stdout)
#define FORi(a,b,c) for(int i=(a);i<(b);i+=c)
#define FORj(a,b,c) for(int j=(a);j<(b);j+=c)
#define FORk(a,b,c) for(int k=(a);k<(b);k+=c)
#define FORp(a,b,c) for(int p=(a);p<(b);p+=c)
#define FORii(a,b,c) for(int ii=(a);ii<(b);ii+=c)
#define FORjj(a,b,c) for(int jj=(a);jj<(b);jj+=c)
#define FORkk(a,b,c) for(int kk=(a);kk<(b);kk+=c)

#define FF(i,a)    for(int i=0;i<(a);i++)
#define FFD(i,a)   for(int i=(a)-1;i>=0;i--)

#define Z(a) (a<<1)
#define Y(a) (a>>1)

const double eps = 1e-6;
const double INFf = 1e10;
const int INFi = 1000000000;
const double Pi = acos(-1.0);

template<class T> inline T sqr(T a){return a*a;}
template<class T> inline T TMAX(T x,T y)
{
	if(x>y) return x;
	return y;
}
template<class T> inline T TMIN(T x,T y)
{
	if(x<y) return x;
	return y;
}
template<class T> inline void SWAP(T &x,T &y)
{
	T t = x;
	x = y;
	y = t;
}
template<class T> inline T MMAX(T x,T y,T z)
{
	return TMAX(TMAX(x,y),z);
}


// code begin
struct trie_node
{
	trie_node* next[52];
	int number;
	int cnt;
};

trie_node mem[20100];
int dx;
trie_node *root;

int T,N;
char in[110];
int ans;

trie_node* CreateNode()
{
	trie_node* p = &mem[dx++];
	FORi(0,52,1)
	{
		p->next[i] = NULL;
	}
	p->number = -1;
	p->cnt = 0;
	return p;
}
int getId(char c)
{
	if(c>='a' && c<='z')
		return c-'a';
	return c-'A'+26;
}
void InsertNode(int l,int r,int flag,int num)
{
	int id,ct=0;
	trie_node* p =root;
	//printf("%d %d %d %d\n",l,r,flag,num);
	do
	{
		id = getId(in[l]);
		if(p->next[id]==NULL)
		{
			p->next[id] = CreateNode();
		}
		p = p->next[id];
		ct++;
		//printf("%d %c\n",num,in[l]);
		if(p->number!=num)
		{
			
			p->cnt++;
			if(p->cnt==N)
			{
				if(ct>ans)
					ans=ct;
			}
		}
		p->number = num;
		//if(l==r) break;
		l+=flag;
	}while(l!=r);

}
int main()
{
	read;
	write;
	int n;
	scanf("%d",&T);
	while(T--)
	{
		scanf("%d",&N);
		dx = 0;
		root = CreateNode();
		ans = 0;
		FORi(0,N,1)
		{
			scanf("%s",in);
			n = strlen(in);
			// 正后缀
			FORj(0,n,1)
			{
				InsertNode(j,n,1,i);
			}
			// 反后缀
			FORj(0,n,1)
			{
				InsertNode(j,-1,-1,i);
			}
		}
		printf("%d\n",ans);
	}
	return 0;
}