Grandparents and grandchildren P87093

Working with trees, to use family terminology is frequent. Thus, is said that a node is parent of another one, or child, or sibling, etcetera, with the equivalent meaning as the tree was genealogical.

Write a program that reads various general trees, and for each one prints all their relationships grandparent–grandchildren.

Input

Input is a sequence of general trees of words, with the format of the exercise . All the words of the same tree are different.

Output

For each given tree, your program must print all the relationships grandparent–grandchildren in lexicogaphically order. Print a line in white after the output of each tree. Follow the format of the instance.