void main()
{
	int i,j=1,n,m;
	char a[100][21];
	scanf("%d",&n);
	for(i=0;i<n;i++)
	{
		scanf("%s",a[i]);
		if((a[i][0]>='a'&&a[i][0]<='z')||(a[i][0]>='A'&&a[i][0]<='Z')||a[i][0]=='_')
		{
			m=0;
			for(j=1;a[i][j]!='\0';j++)
			{
				if((a[i][j]>='a'&&a[i][j]<='z')||(a[i][j]>='A'&&a[i][j]<='Z')||a[i][j]=='_'||(a[i][j]>='0'&&a[i][j]<='9'))continue;
				else {printf("no\n");m=1;break;}
			}
			if(m=1&&j==strlen(a[i]))printf("yes\n");
		}
		else printf("no\n");
	
	}

}