In some simplistic DBMS named PreQueL, the only column type allowed is CHAR(1) (a single character), and furthermore, its values are restricted to English upper-case letters ('A' to 'Z'). Table may contain up to 9 columns, numbered from 1 to 9. Tables themselves are named with lower-case English letters ('a' to 'z').
The only database query possible first joins all the tables, then selects some rows according to conditions in one of two forms: either < column>=< value> or < column1>=< column2>, for example a2=A or b1=c4. All conditions must hold simultaneously, as if they were connected by 'AND' operator.
You must write a PreQueL processor, which, given a tables and a set of conditions, will produce query result, i.e. those rows of a join satisfying all the conditions. Resulting rows must be sorted alphabetically.