#include <stdio.h>
#include <string.h>
#include <algorithm>
#define MN 10000

int n,a[10],b[1<<10],f[6][1<<10];
char c[MN+5];

void solve(){
    memset(a,0,sizeof(a));
    memset(f,0x3f,sizeof(f));
    scanf("%d",&n);
    for(int i=1;i<=n;i++){
        scanf("%*4s%c",&c[i]);
        a[c[i]-'0']++;
    }
    for(int S=0;S<(1<<10);S++){
        b[S] = 0;
        for(int i=0;i<10;i++)
            if((S&(1<<i))==0) b[S] += a[i];
    }
    f[0][0]=0;
    for(int d=1;d<=5;d++){
        int *now = f[d];
        int *last = f[d-1];
        for(int Snow=0;Snow<(1<<10);Snow++){
            for(int Slast=0;Slast<(1<<10);Slast++){
                if((Snow&Slast)!=Slast) continue;
                now[Snow] = std::min(now[Snow],std::max(last[Slast],b[Snow^Slast]));
            }
        }
    }
    printf("%d\n",f[5][(1<<10)-1]);
}

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