import json


class Node:
    def __init__(self, data):
        self.value = data
        self.left = None
        self.right = None

    def __repr__(self):
        return "<Node val=%s left=%s right=%s>" % (self.value, self.left,
                                                   self.right)


st = json.loads(input())
head = Node(st.pop(0))
l = [head]
while st:
    cnt = len(l) * 2
    lc = []
    while st and cnt:
        cnt -= 1
        lc.append(Node(n) if (n := st.pop(0)) else None)
    j = 0
    for i in l:
        if i and j < len(lc):
            i.left = lc[j]
            j += 1
            if j < len(lc):
                i.right = lc[j]
                j += 1
    l = lc

...
...