#include <bits/stdc++.h>
using namespace std;
int main()
{
    //ios_base::sync_with_stdio(false);
    //cin.tie(NULL);
    int t;
    cin>>t;//no of test cases
    while(t>0)
    {
        int n;
        cin>>n;//no of dishes in each test case
        int freq[26];//frequency array to count the number of occurance of a letter in the dishes for each test case 
        memset(freq,0,sizeof(freq));//initializing to zero
        int temp=n;
        int ans=0;
        while(n>0)
        {
            string str;
            cin>>str;
            int counts[26];//frequency array to count the occurance of letter in a string
            memset(counts,0,sizeof(counts));
            for(int i=0;i<str.length();i++)
            {
                if(counts[str[i]-'a']==0)//checking if the letter has already been repeated
                {
                    freq[str[i]-'a']++;//incrementing the count of letter in the dish by one
                    counts[str[i]-'a']=1;
                }
            }
            n--;
        }
        for(int i=0;i<26;i++)
        {
            if(freq[i]==temp)//checking if the letter is present in each string or not.
            {
                ++ans;
            }
        }
        printf("%d\n",ans);//printing the number of secret ingredients
        t--;
    }
    return 0;
}