C语言完成以下代码：给定一棵有根结点的二叉树，规定连接两个结点的每条边长度为1。定义树的深度（Depth）为树中各结点的最大层数，也称为树的高度（Height）。根结点处在第1层，深度为1。

以下是C语言代码实现：

#include <stdio.h>
#include <stdlib.h>

struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

/* 计算树的深度 */
int maxDepth(struct TreeNode* root) {
    if (root == NULL) {
        return 0;
    } else {
        int leftDepth = maxDepth(root->left);
        int rightDepth = maxDepth(root->right);
        return (leftDepth > rightDepth) ? (leftDepth + 1) : (rightDepth + 1);
    }
}

/* 创建二叉树 */
struct TreeNode* createTree() {
    int val;
    scanf("%d", &val);
    if (val == -1) {
        return NULL;
    } else {
        struct TreeNode* root = (struct TreeNode*)malloc(sizeof(struct TreeNode));
        root->val = val;
        root->left = createTree();
        root->right = createTree();
        return root;
    }
}

int main() {
    struct TreeNode* root = createTree();
    int depth = maxDepth(root);
    printf("Depth of the tree: %d\n", depth);
    return 0;
}

输入样例：

1 2 -1 -1 3 4 -1 -1 5 -1 -1

输出样例：

Depth of the tree: 3