Sum of Leaf Nodes

Write a function that computes the sum of the values of all leaf nodes in a binary tree. The input will be a level-order representation of the binary tree where none of the integers will be negative and a value of -1 indicates the absence of a node. The output should be a single integer representing the sum of all leaf nodes. Input Format: A single line of space-separated integers representing the level-order traversal of the tree. Output Format: A single integer value representing the sum of all leaf nodes. Example: Input: 1 2 3 -1 -1 -1 -1 Output: 5