#include <map>

#include <set>

#include <list>

#include <cmath>

#include <queue>

#include <stack>

#include <cstdio>

#include <vector>

#include <string>

#include <cctype>

#include <complex>

#include <cassert>

#include <utility>

#include <cstring>

#include <cstdlib>

#include <iostream>

#include <algorithm>

using namespace std;

typedef pair<int,int>P;

typedef long long ll;

#define lson l,m,rt<<1

#define pi acos(-1.0)

#define rson m+1,r,rt<<11

#define All 1,N,1

#define N 10000010

#define read freopen("in.txt", "r", stdin)

const ll  INFll = 0x3f3f3f3f3f3f3f3fLL;

const int INF= 0x7ffffff;

const int mod =  ;

struct Trie{

    int ch[N][];

    int val[N],num;

    void init(){

        num=;

        memset(ch[],,sizeof(ch[]));

        memset(val,,sizeof(val));

    }

    //建树

    void build(char *s){

        int u=,len=strlen(s);

        for(int i=;i<len;++i){

            int v=s[i]-'';

            if(!ch[u][v]){

                memset(ch[num],,sizeof(ch[num]));

                ch[u][v]=num++;

            }

            u=ch[u][v];

            val[u]++;

        }

    }

     //bfs

    ll query(){

        queue<P>q;

        ll maxv=;

        q.push(P(,));

        while(!q.empty()){

            P p=q.front();

            q.pop();

            int u=p.first;

            int h=p.second;

            maxv=max(maxv,1LL*val[u]*h);

            for(int i=;i<;++i){

                if(ch[u][i]){

                    q.push(P(ch[u][i],h+));

                }

            }

        }

       return maxv;

    }

}trie;

int main()

{

    int t,n;

    char str[];

    scanf("%d",&t);

    for(int o=;o<t;++o){

        trie.init();

        scanf("%d",&n);

        for(int i=;i<n;++i){

            scanf("%s",str);

            trie.build(str);

        }

        printf("%lld\n",trie.query());

    }

return ;

}