Find Leaf Nodes in a Tree

You are given a tree represented as a series of node descriptions. Each node is described by a list of integers where the first integer represents the node's label, the second integer represents the number of children (denoted by K), and if K > 0 then the next K integers represent the node's children labels.

Your task is to identify all leaf nodes (nodes with no children) and output their labels in increasing order.

In mathematical form, a node is a leaf if and only if $$K=0$$.

inputFormat

The input is provided via stdin in the following format:

• The first line contains a single integer N representing the number of nodes.
• Each of the following N lines describes a node with space-separated integers. The first integer is the node label, the second integer is K (the number of children), followed by K integers representing the children labels (if any).

outputFormat

Output the labels of the leaf nodes in increasing order. The output should be printed to stdout as a single line of space-separated integers.

5
1 2 2 3
2 0
3 2 4 5
4 0
5 0

2 4 5