#include <bits/stdc++.h>
using namespace std;
int n, cnt[15], a[2048], dp[15][2048];
void solve() {
    scanf("%d", &n);
    memset(cnt, 0, sizeof cnt);
    memset(a, 0, sizeof a);
    memset(dp, 0, sizeof dp);
    for (int i = 1; i <= n; i++) {
        char s[10];
        scanf(" %s", s);
        cnt[s[4] - '0']++;
    }
    for (int i = 0; i < (1 << 10); i++) {
        for (int j = 0; j < 10; j++)
            if (((i >> j) & 1) == 0) a[i] += cnt[j];
    }
    for (int i = 1; i <= 5; i++) {
        for (int j = 0; j < (1 << 10); j++) {
            dp[i][j] = n * 10;
            for (int k = 0; k < (1 << 10); k++) {
                if ((j & k) != k) continue;
                dp[i][j] = min(dp[i][j], max(dp[i - 1][k], a[j & (~k)]));
            }
        }
    }
    printf("%d\n", dp[5][1023]);
}
int main() {
    int T;
    cin >> T;
    while (T--) {
        solve();
    }
    return 0;
}