#include <iostream>
#include <fstream>
#include <math.h>
#include <sstream>
#include <string>

using namespace std;


string get_line(fstream &f)
{
	char temp[1024];
	string t;
	f.getline(temp,1024);
	t = temp;
	return t;
}


int main()
{
fstream file("biomed.in");

string input = get_line(file);

stringstream p1(input);

int sets;

p1 >> sets;

for(int a = 0; a < sets; a++)
{
input = get_line(file);
stringstream p2(input);
int n;
p2 >> n;

string main_string = get_line(file);
string minions[100];

for(int i = 0; i < n; i++)
	minions[i] = get_line(file);

int min_value[1001];

for(int i = 0; i < 1001; i++)
	min_value[i] = -1;

for(int i = 0; i < n; i++)
{
	if (minions[i] == main_string.substr(0,minions[i].length()))
		min_value[minions[i].length()] = 1;
}

for(int i = 2; i <= main_string.length() + 1; i++)
{
	for(int j = 1; j <= i; j++)
	{
		for(int k = 0; k < n; k++)
		{
			if (main_string.substr(0,j).append(minions[k]) == main_string.substr(0,i) && min_value[j] > 0)
			{
				//cout << main_string.substr(0,j).append(minions[k]);
				//cout << "\n";
				if ((min_value[j] + 1) < min_value[i] || min_value[i] == -1)
					min_value[i] = min_value[j] + 1;
			}
		}

	}
}
cout << "Data Set " << a + 1 << ":\n";
if (min_value[main_string.length()] > 0)
cout << min_value[main_string.length()] << "\n";
else
cout << "Impossible\n";

}

}