
int main()
{
int n;
scanf("%d",&n);
char s[100];
int m;
int i;
int p;
for(i=1;i<=n;i++)
{
	scanf("%s",s);
	for(m=0;s[m];m++)
	{
		if((s[0]=='_')||(s[0]>='A'&&s[0]<='Z')||(s[0]>='a'&&s[0]<='z'))
			p=1;
		else
		{
			p=0;
			break;
		}
		if((s[m]=='_')||(s[m]>='A'&&s[m]<='Z')||(s[m]>='a'&&s[m]<='z')||(s[m]>='0'&&s[m]<='9'))
			p=1;
		else
		{
			p=0;
			break;
		}
	}
	if(p==1)
		printf("yes\n");
	else
		printf("no\n");

}
			
		

return 0;
}


	
