import java.util.*;

class Tree {

private final String label;

private final List<Tree> children;

public Tree(String label) {

this(label, new ArrayList<>());

}

public Tree(String label, List<Tree> children) {

this.label = label;

this.children = children;

}

public static Tree of(String label) {

return new Tree(label);

}

public static Tree of(String label, List<Tree> children) {

return new Tree(label, children);

}

@Override

public boolean equals(Object o) {

if (this == o) return true;

if (o == null || getClass() != o.getClass()) return false;

Tree tree = (Tree) o;

return label.equals(tree.label)

&& children.size() == tree.children.size()

&& children.containsAll(tree.children)

&& tree.children.containsAll(children);

}

@Override

public int hashCode() {

return Objects.hash(label, children);

}

@Override

public String toString() {

return "Tree{" + label +

", " + children +

"}";

}

public Tree fromPov(String fromNode) {

throw new UnsupportedOperationException("Please implement the Pov.fromPov() method.");

}

public List<String> pathTo(String fromNode, String toNode) {

throw new UnsupportedOperationException("Please implement the Pov.pathTo() method.");

}

}