Check if a Tree is Full Binary Tree or Not

#include<stdio.h>
#include<stdlib.h>
#include<stdbool.h>
struct Node
{
    int key;
    struct Node *left, *right;
};
struct Node *newNode(char k)
{
    struct Node *node = (struct Node*)malloc(sizeof(struct Node));
    node->key = k;
    node->right = node->left = NULL;
    return node;
}

bool isFullTree(struct Node *root)
{
    if(root==NULL)
    {
        return true;
    }
         else if((root->left==NULL)&&(root->right!=NULL))
        {
            return false;
        }
        else if((root->left!=NULL)&&(root->right==NULL))
        {
            return false;
        }
        else if((root->left==NULL)&&(root->right==NULL))
        {
            return true;
        }
else
        {
            return (isFullTree(root->left)&&isFullTree(root->right));
        }
}

int main()
{
    struct Node* root = NULL;
    root = newNode(10);
    root->left = newNode(20);
    root->right = newNode(30);
 root->left->right = newNode(40);
    root->left->left = newNode(50);
    root->right->left = newNode(60);
    root->right->right = newNode(70);
    root->left->left->left = newNode(80);
    root->left->left->right = newNode(90);
    root->left->right->left = newNode(80);
    root->left->right->right = newNode(90);
    root->right->left->left = newNode(80);
    root->right->left->right = newNode(90);
    root->right->right->left = newNode(80);
    root->right->right->right = newNode(90);
    if (isFullTree(root))
        printf("The Binary Tree is full\n");
    else
        printf("The Binary Tree is not full\n");

    return(0);
}