/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
    public int minDepth(TreeNode root) {
        if(root==null)
        {
            return 0;
        }
      if(root.left==null) return(minDepth(root.right)+1);
      if(root.right==null) return (minDepth(root.left)+1);
        return ( Math.min(minDepth(root.left),minDepth(root.right))+1);
      }
}