from collections import deque

class TreeNode:
    def __init__(self, val=0, left=None, right=None):
        self.val = val
        self.left = left
        self.right = right

def constructTree(nodes):
    if not nodes:
        return None

    root = TreeNode(nodes[0])
    q = deque()
    q.append(root)
    i = 1

    while q and i < len(nodes):
        parent = q.popleft()
        leftVal = nodes[i]
        rightVal = nodes[i+1] if i+1 < len(nodes) else None
        i += 2

        if leftVal is not None:
            parent.left = TreeNode(leftVal)
            q.append(parent.left)

        if rightVal is not None:
            parent.right = TreeNode(rightVal)
            q.append(parent.right)

    return root

def maxwidth(root):
    if not root:
        return 0

    maxWidth = float('-inf')
    q = deque()
    q.append((root, 0))

    while q:
        size = len(q)
        left, right = float('inf'), float('-inf')

        for _ in range(size):
            node, pos = q.popleft()
            left = min(left, pos)
            right = max(right, pos)

            if node.left:
                q.append((node.left, 2 * pos))

            if node.right:
                q.append((node.right, 2 * pos + 1))

        maxWidth = max(maxWidth, right - left + 1)

    return maxWidth

# Example usage:
n = int(input())
nodes = list(map(int, input().split()))
root = constructTree(nodes)
maxWidth = maxwidth(root)
print(maxWidth)