int main()
{
    int n,l,i,j;
	scanf("%d",&n);
	char s[81];
	for(i=0;i<n;i++){
		gets(s);
		l=strlen(s);
		if(l==0){
			i--;
			continue;
		}
		for(j=0;j<l;j++){
			if((s[0]>='a'&&s[0]<='z')||(s[0]>='A'&&s[0]<='Z')||s[0]=='_'){
					if((s[j]>='a'&&s[j]<='z')||(s[j]>='A'&&s[j]<='Z')||s[j]=='_'||(s[j]>='0'&&s[j]<='9')){
						if(j==l-1){
		                        printf("yes\n");
						}
					}
					else{
					printf("no\n");
					break;
					}
			}
				else{
					printf("no\n");
					break;
					}
		}
	}
	return 0;
}
