int main(){
    char zf[256];
	int i,j,n,count=1;
    scanf("%d",&n);

	for(i=0;i<n;i++){
		scanf("%s",zf);
		if(zf[0]>'z'||(zf[0]<'a'&&zf[0]>'Z')||zf[0]<'A'){
			if(zf[0]!='_'){
			count=0;
			printf("no\n");
			continue;
		}
		}
		for(j=1;zf[j]!='\0';j++){
			if(zf[j]=='_'||(zf[j]>='A'&&zf[j]<='Z')||(zf[j]>='0'&&zf[j]<='9')||(zf[j]>='a'&&zf[j]<='z'))
				count=1;
			else{
				count=0;
				printf("no\n");
				break;
			}
					
	}if(count==1)
		printf("yes\n");
	}
	return 0;

}