void main()
{
	int n,i,sum,count=0;
	char num[30][21]={'\0'};
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%s",num[i]);
	}

	for(i=0;i<n;i++)
	{
		int tmp=0,k=0,len;
			len=strlen(num[i]);

		while(num[i][k]!='\0')
		{

			if(k==0)
			{
				if((num[i][k]>='A' && num[i][k]<='Z') || (num[i][k]>='a' && num[i][k]<='z') || num[i][k]=='_') 
				{
					tmp++;
				}
				else 
				{
					printf("no\n");
					break;
				}
			}
			else
			{
				if((num[i][k]>='A' && num[i][k]<='Z') || (num[i][k]>='a' && num[i][k]<='z') || (num[i][k]>='0' && num[i][k]<='9') || num[i][k]=='_') 
				{
					tmp++;
				}
				else
				{
					printf("no\n");
					break;
				}
			}
			k++;
		}
		if(tmp==len) printf("yes\n");
	}
}

/*?? - ?? C ????   
 
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???? 
??????n???n?????????????????????????????20?
 
???? 
?????????????C????????????yes?????no?
 
???? 
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*/