vector<int> a;
int val(char c) {
  if (c >= '0' && c <= '9')
    return (int)c - '0';
  else
    return (int)c - 'A' + 10;
}
void init() {
  int T;
  cin >> T;
  while (T--) {
    int N, B, ans = -1;
    cin >> N;
    string s;
    for (int i = 1; i <= N; i++) {
      cin >> B >> s;
      if (B != -1) {
        int len = s.size();
        int power = 1;
        int num = 0;
        int i;
        for (i = len - 1; i >= 0; i--) {
          num += val(s[i]) * power;
          power = power * B;
          if (num > 1e12)
            break;
        }
        if(i==-1) ans = num;
      } else {
        int maxi = -1;
        for (int i = s.size() - 1; i >= 0; i--)
          maxi = max(val(s[i]), maxi);
         if (s.size() == 1)
         a.pb(val(s[s.size() - 1]));
        for (int j = maxi + 1; j <= 36; j++) {
          int len = s.size();
          int power = 1;
          int num = 0;
          int i;

          for (i = len - 1; i >= 0; i--) {
            num += val(s[i]) * power;
            power = power * j;
            if (num > 1e12)
              break;
          }
          if(i==-1) a.pb(num);
        }
      }
    }
    if (ans != -1)
      cout << ans << endl;
    else {
      int flag = 0, num;
      for (int i = 0; i < a.size(); i++) {
        int cnt = count(a.begin(), a.end(), a[i]);
        if (cnt == N) {
          num = a[i];
          flag = 1;
          break;
        }
      }
      if (flag == 1)
        cout << num << endl;
      else
        cout << -1 << endl;
      a.clear();
    }
  }
}