def inOrderTraversal (currentNode):
    print(tree[currentNode][2] != -1
    if tree[currentNode][0] != -1:
        inOrderTraversal(tree[currentNode][0])
    if tree[currentNode][2] != -1:
          inOrderTraversal(tree[currentNode][2])

tree = [[5,"Marko",1],
        [3,"Peter",2],
        [-1,"Sam",12],
        [4,"Ollie M",-1],
        [7,"Ollie J",-1],
        [6,"Alex J",8],
        [-1,"Abdullah",14],
        [-1,"Max",-1],
        [11,"Charlie",9],
        [-1,"Eghosa",10],
        [15,"Joe",-1],
        [-1,"Ben",-1],
        [13,"Toby",-1],
        [-1,"Sasha",-1],
        [-1,"Alex B",-1],
        [-1,"Harry",-1]]

inOrderTraversal(0)