#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<int, ll> pil;
typedef pair<ll, int> pli;
typedef pair<ll, ll>pll;

const ll MOD = 1e9 + 7;
const int MAXN = 1e5;

ll gcd(ll a, ll b)
{
    return b == 0 ? a : gcd(b, a % b);
}
ll lcm(ll a, ll b)
{
    return a / gcd(a, b) * b;
}
ll pow(ll a, ll b)
{
    ll res = 1;
    while (b)
    {
        if (b & 1) res = res * a % MOD;
        a = a * a % MOD;
        b >>= 1;
    }
    return res;
}

struct unionset
{
    int size;
    int fa[30000];
    void clear(int jj)
    {
        for (int i = 0; i <= jj; i++)
        {
            fa[i] = i;
        }
    }
    int getfa(int x)
    {
        return fa[x] == x ? x : fa[x] = getfa(fa[x]);
    }
    bool merge(int a, int b)
    {
        int faa = getfa(a);
        int fbb = getfa(b);
        if (faa > fbb)swap(faa, fbb);
        if (faa != fbb)
        {
            fa[fbb] = faa;
            return true;
        }
        return false;
    }
};
struct graph
{
    struct edge
    {
        int v, nxt;
        int d;
        edge(int vv = 0, int dd = 0, int nn = 0)
        {
            v = vv;
            d = dd;
            nxt = nn;
        }
    };
    static const int MAXN = 1e5;
    static const int MAXM = 1e6;
    vector<int>h;
    vector<edge>e;

    graph()
    {
        h.clear();
        e.clear();
        for (int i = 0; i < MAXN; i++)
        {
            h.push_back(-1);
        }
    }
    void addedge(int u, int v, int d = 0)
    {
        e.push_back(edge());
        e[e.size() - 1].v = v;
        e[e.size() - 1].d = d;
        e[e.size() - 1].nxt = h[u];
        h[u] = e.size() - 1;
    }
};

int dp[10][(1 << 12)];
int ct[(1 << 12)];
int car[11];
char s[100];
int main()
{
    int T;
    cin >> T;
    while (T--)
    {
        memset(car, 0, sizeof car);
        memset(dp, -1, sizeof dp);
        memset(ct, 0, sizeof ct);
        int n;
        scanf("%d", &n);

        for (int i = 0; i < n; i++)
        {
            scanf("%s", s);
            car[s[4] - '0']++;
        }
        for (int i = 0; i < (1 << 10); i++)
        {
            int now = 0;
            for (int j = 0; j < 10; j++)
            {
                if ((i & (1 << j)) != 0)
                {
                    now += car[j];
                }
            }
            ct[i] = now;
        }

        for (int i = 0; i < (1 << 10); i++)
        {
            dp[0][i] = n - ct[i];
        }

        for (int i = 1; i < 5; i++)
        {
            for (int j = 0; j < (1 << 10); j++)
            {
                for (int k = 0; k < (1 << 10); k++)
                {
                    if (j & k)continue;
                    if (dp[i][j | k] == -1)dp[i][j | k] = max(dp[i - 1][k], n - ct[j]);
                    else dp[i][j | k] = min(dp[i][j | k], max(dp[i - 1][k], n - ct[j]));
                }
            }
        }
        int ans = 1e9;
        for (int i = 0; i < (1 << 10); i++)
        {
            ans = min(ans, dp[4][i]);
        }
        printf("%d\n", ans);
    }
}