class Solution {
    int sum=0;
    
    void helper(TreeNode root)
    {
        if(root==null)return ;
        // System.out.print(root.val);
        
         if((root.left.left==null)&&(root.left.right==null))
        {
            System.out.print(root.left.val);
            sum=sum+root.left.val;
            return ;
        }
        
       
        
        helper(root.left);
        helper(root.right);
        
    }
    public int sumOfLeftLeaves(TreeNode root) {
        
        // if()
        
        helper( root);
        return sum;
        
    }
}