#include <cstdio>
#include <algorithm>
#include <vector>
#include <cstring>
using namespace std;

#define LL long long

const int MX = 10000 + 233;
int C[10] ,cnt[1 << 10];

int dp[6][1 << 10] ,n;
int check(int x){
    memset(dp ,0 ,sizeof dp);
    dp[0][0] = 1;
    for(int i = 1 ; i <= 5 ; ++i){
        for(int j = 0 ; j < 1 << 10 ; ++j){
            for(int S = j ;  ; S = (S - 1) & j){
                dp[i][j] |= dp[i - 1][S] && (n - cnt[j ^ S] <= x);
                if(!S) break; 
            }
        }
    }
    int ok = 0;
    for(int i = 0 ; i < 1 << 10 && !ok ; ++i)
        ok |= dp[5][i];
    return ok;
}

void solve(){
    memset(C ,0 ,sizeof C);
    memset(cnt ,0 ,sizeof cnt);
    scanf("%d" ,&n);
    for(int i = 1 ; i <= n ; ++i){
        char str[233];
        scanf("%s" ,str);
        C[str[4] - '0']++;
    }
    for(int i = 0 ; i < 1 << 10 ; ++i){
        for(int j = 0 ; j < 10 ; ++j){
            if((i >> j) & 1) cnt[i] += C[j];
        }
    }
    int l = 0 ,r = 10001 ,mid;
    while(l <= r){
        mid = (l + r) >> 1;
        if(check(mid)) r = mid - 1;
        else l = mid + 1;
    }
    printf("%d\n" ,r + 1);
}

int main(){
    int T; scanf("%d" ,&T);
    while(T--) solve();
    return 0;
}