#include<stdio.h>

 #include<string.h>

 #include<iostream>

 #include<string>

 #include<algorithm>

 using namespace std;

 const int maxn=;

 int nxt[][maxn],ext[][maxn];

 char s[][maxn];

 int len[],ans[maxn];

 void EKMP(char s[],char t[],int lens,int lent,int c){

     int i,j,p,l,k;

     nxt[c][]=lent;j=;

     while(j+<lent&&t[j]==t[j+])j++;

     nxt[c][]=j;

     k=;

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

         p=nxt[c][k]+k-;

         l=nxt[c][i-k];

         if(i+l<p+)nxt[c][i]=l;

         else{

             j=max(,p-i+);

             while(i+j<lent&&t[i+j]==t[j])j++;

             nxt[c][i]=j;

             k=i;

         }

     }

     j=;

     while(j<lens&&j<lent&&s[j]==t[j])j++;

     ext[c][]=j;k=;

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

         p=ext[c][k]+k-;

         l=nxt[c][i-k];

         if(l+i<p+)ext[c][i]=l;

         else{

             j=max(,p-i+);

             while(i+j<lens&&j<lent&&s[i+j]==t[j])j++;

             ext[c][i]=j;

             k=i;

         }

     }

 }

 int main(){

     int T;

     scanf("%d",&T);

     while(T--){

         memset(ans,0x3f,sizeof(ans));

         int n;

         scanf("%d",&n);

         for(int i=;i<=n;++i)scanf("%s",s[i]);

         for(int i=;i<=n;++i)len[i]=strlen(s[i]);

         s[][len[]]='#';

         for(int i=;i<=len[];++i)s[][len[]+i]=s[][len[]-i];

         s[][len[]+len[]+]=;

         len[]=strlen(s[]);

         int maxx=;

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

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

                 int cnt=;

                 EKMP(s[j],s[]+i,len[j],len[]-i,j);

                 for(int k=;k<len[j];++k){

                     if(ext[j][k]>cnt)cnt=ext[j][k];

                 }

                 if(cnt<ans[i])ans[i]=cnt;

             }

             if(ans[i]>maxx)maxx=ans[i];

         }

         printf("%d\n",maxx);

     }

     return ;

 }