Bob enjoys playing computer games, especially strategic games, but sometimes he
cannot find the solution fast enough and then he is very sad. Now he has the
following problem. He must defend a medieval city, the roads of which form a
tree. He has to put the minimum number of soldiers on the nodes so that they
can observe all the edges. Can you help him?

Your program should find the minimum number of soldiers that Bob has to put
for a given tree.

The input file contains several data sets in text format. Each data set represents
a tree with the following description:

the number of nodes
the description of each node in the following format
node_identifier:(number_of_roads) node_identifier1 node_identifier2 ... node_identifier
or
node_identifier:(0)

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