def condense_sets(sets):
    result = []
    for candidate in sets:
        for current in result:
            if candidate & current:   # found overlap
                current |= candidate  # combine (merge sets)
 
                # new items from candidate may create an overlap
                # between current set and the remaining result sets
                result = condense_sets(result) # merge such sets
                break
        else:  # no common elements found (or result is empty)
            result.append(candidate)
    return result
 
sets = eval(input())
print(condense_sets(sets))

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[ {1,2}, {2,3}, {3,4}, {10, 11, 12}, {10, 13}, {20, 21} ]