/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p==null&&q==null)return true;
        if(p==null&&q!=null)return false;
        if(p!=null&&q==null)return false;
        if(isSameTree(p.left,q.left)&&isSameTree(p.right,q.right)&&(p.val==q.val))return true;
        else return false;
    }
}