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Problem Statement

You are to write a program which reads 2 series of letters from a line, place place them each into a set, and display either the intersection or union of the two sets.

Input Specification

The file SETS.IN will contain lines consisting of two groups of letters and an operator. All letters will be in uppercase (A-Z) and the two groups of letters will be separated by a single space. After the second set of letters will be either the symbol + (for union) or * (for intersection). Each group of letters will contain at least one letter. There is no special marker for the termination of this file.

Output Specification

In the output file SETS.OUT, all sets should be enclosed in the set brackets { and }. Sets should contain the letters that are members of that set in alphabetic order, with a comma between elements. Each line should be in the form:

SETA operator SETB = NEWSET

Sample Input

ABC ABD *
ABC ABD +
AB CD *

Sample Output

{A,B,C} * {A,B,D} = {A,B}
{A,B,C} + {A,B,D} = {A,B,C,D}
{A,B} * {C,D} = {}

This is a modified version of a practice problem from 1993.