//poj:2744
#include<stdio.h>
#include<string.h>
int t,n;
char str[101][101];
int searchMaxSubString(char *source)
{
int subStrLen=strlen(source);
int sourceStrLen=strlen(source);
int i,j;
bool foundMaxSubStr;
char subStr[101];
char revSubStr[101];
while(subStrLen>0)
{
for(i=0;i<=sourceStrLen-subStrLen;i++)
{
strncpy(subStr,source+i,subStrLen);
strncpy(revSubStr,source+i,subStrLen);
subStr[subStrLen]=revSubStr[subStrLen]='\0';
strrev(revSubStr);
foundMaxSubStr=true;
for(j=0;j<n;j++)
{
if(strstr(str[j],subStr)==NULL && strstr(str[j],revSubStr)==NULL)
{
foundMaxSubStr=false;
break;
}
}
if(foundMaxSubStr) return subStrLen;
}
subStrLen--;
}
return 0;
}
int main()
{
int i,minStrLen,subStrLen;
char minStr[101];
scanf("%d",&t);
while(t--)
{
scanf("%d",&n);
minStrLen=100;
for(i=0;i<n;i++)
{
scanf("%s",str[i]);
if(strlen(str[i])<minStrLen)
{
strcpy(minStr,str[i]);
minStrLen=strlen(minStr);
}
}
subStrLen=searchMaxSubString(minStr);
printf("%d\n",subStrLen);
}
return 0;
}