#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<ll, ll>;
const ll MOD = 1e9 + 7, N = 1e5 + 10;
string d(ll a) {
  string s = to_string(a);
  while (s.length() < 4) {
    s = "0" + s;
  }
  return s;
}
void test() {
  ll n;
  cin >> n;
  vector<string> a(n);
  vector<ll> cnt(n);
  for (ll i = 0; i < n; i++) {
    cin >> a[i];
  }
  ll ans = 0;
  for (ll i = 0; i < n; i++) {
    ll c = 0;
    vector<ll> tt(4);
    for (ll j = 0; j < 4; j++) {
      tt[j] = a[i][j] - '0';
    }
    for (ll j = 0; j < n; j++) {
      if (i == j) continue;
      if (a[i] == a[j]) {
        if (!cnt[i]) ans++;
        cnt[i] = 1;
        ll to_make = a[i][c] - '0';
        to_make++;
        to_make %= 10;
        if (to_make == tt[c]) {
          c++;
          to_make = a[i][c] - '0';
        }
        a[i][c] = char('0' + to_make);
        i--;
        break;
      }
    }
  }
  cout << ans << '\n';
  for (ll i = 0; i < n; i++) {
    cout << a[i] << '\n';
  }
  return;
}
int32_t main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL);
  ll tt = 1;
  cin >> tt;
  for (ll i = 0; i < tt; i++) test();
  return 0;
}
