# your code goes here
class BinaryTree:
    def __init__(self, root):
        self.key = root 
        self.left_child = None 
        self.right_child = None 

    def insert_left(self, new_node):
        if (self.left_child is None):
            self.left_child = BinaryTree (new_node) 
        else:
            t = BinaryTree(new_node) 
            t.left_child = self.left_child 
            self.left_child = t 
    def insert_right(self, new_node):
        if self.right_child is None:
            self.right_child = BinaryTree(new_node) 
        else:
            t = BinaryTree(new_node)
            t.right_child = self.right_child 
            self.right_child = t 
    def get_right_child(self):
        return self.right_child 
    def get_left_child(self):
        return self.left_child 
    def set_root_val(self, obj):
        self.key = obj 
    def get_root_val(self):
        return self.key

r = BinaryTree('a') 

print("-1", r.get_root_val()) 

print("-2",r.get_left_child()) 

r.insert_left('b') 

print("-3",r.get_left_child()) 

print("-4", r.get_left_child().get_root_val())

r.insert_right('c')

print("-5", r.get_right_child()) 

print("-6", r.get_right_child().get_root_val()) 

r.get_right_child().set_root_val('hello') 

print("-7",r.get_right_child().get_root_val())