Blue Jeans

3
2
GATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
3
GATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATACCAGATA
GATACTAGATACTAGATACTAGATACTAAAGGAAAGGGAAAAGGGGAAAAAGGGGGAAAA
GATACCAGATACCAGATACCAGATACCAAAGGAAAGGGAAAAGGGGAAAAAGGGGGAAAA
3
CATCATCATCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
ACATCATCATAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AACATCATCATTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT

no significant commonalities
AGATAC
CATCATCAT

#include<iostream>
#include <string>
using namespace std;
string a[1000];
int main()
{int t,i,n,j,k;
cin>>t;
	while(t--)
	{cin>>n;
		string b="";
		for(i=0;i<n;i++)
	cin>>a[i];

	for(i=0;i<=a[0].size();i++)
	{
		for(j=0;j<=a[0].size();j++)
		{bool p=0;
			string temp = a[0].substr(j, i);
		for(k=1;k<n;k++)
		{if (a[k].find(temp) == string::npos)
			{p=1;
			break;}
		}
	if(p==0)
	if(temp.length()>b.length())b=temp;
else if(temp.length()==b.length()&&b>temp)b=temp;
		}


	}

if(b.size()<3)
		printf("no significant commonalities\n");
	else
        cout<<b<<endl;





	}


return 0;}