int main()
{
	int t;
	scanf("%d",&t);

	char str[10][100000];
	char (*p)[100000];
	char *c;
	char a[1];
	gets(a);

	int letter[26]={0};
	int *count;

	for (p=str;p<str+t;p++)
		gets(*p);

	for (p=str;p<str+t;p++)
	{
		for (c=*p;*c!=0;c++)
		{
			count=letter+*c-'a';
			(*count)++;
		}
		for (c=*p;*c!=0;c++)
		{
			count=letter+*c-'a';
			/*printf("%c %d\n",*c,*count);//for test*/
			if (*count==1)
			{
				printf("%c\n",count-letter+'a');
				break;
			}
		}
		if (*c==0) printf("no\n");
		for (count=letter;count<letter+26;count++)
			*count=0;
	}
	return 0;
	}



