//**************************************
//*  ????????????          *
//*  ??????                      *
//*  ?????2011?10?31?          *
//**************************************


int main()
{
	int t, i, j, k, n, p, q;
	char str[100000];
	cin >> t;//t?????????
	for(i = 1; i <= t; i ++)
	{
		cin >> str;//?????
		n = strlen(str);//n????????
		q = 0;//q????????????
		for(j = 0; j < n; j ++)
		{
			p = 0;//p?????????????
			for(k = 0; k < n; k ++)
			{
				if(k != j)//???????????
				{
					if(str[j] == str[k])//????????
					{
						p = 1;//p???1
						q = q + p;//????q?
						break;//??????
					}
				}
			}
			if(p == 0)//???????????
			{
				cout << str[j] << endl;//???????
				break;//????
			}
		}
		if(q == n)//?????????????????
			cout << "no" << endl;//??no
	}
	return 0;
}