#include <cstdio>
#include <iostream>
#include <vector>
using namespace std;
int main()
{
int casesCount, mobileCount, dif;
vector<string> mobileNumbers;
string jalilNumber;
scanf("%d", &casesCount);
for (int caseId = 1; caseId <= casesCount; ++caseId)
{
scanf("%d", &mobileCount);
printf("Case %d:\n", caseId);
mobileNumbers = vector<string>(mobileCount);
for (int i = 0; i < mobileCount; ++i)
{
cin >> mobileNumbers[i];
}
cin >> jalilNumber;
for (auto ¤tNumber : mobileNumbers)
{
dif = 0;
for (int i = 0; i < currentNumber.size(); ++i)
{
if (currentNumber[i] != jalilNumber[i])
{
++dif;
}
}
if (dif <= 1)
{
printf("%s\n", currentNumber.c_str());
}
}
}
return 0;
}