How To Lock Direction While Jumping?

So I have this movement script but I want to be able to not move direction while jumping. At the moment, I can fly in any direction. I'm brand new to C# so obviously I have no idea, it's all a foreign language to me. Let me know what I need to change, thanks:

 using UnityEngine;
 using System.Collections;
 
 public class PlayerMovement : MonoBehaviour {
     
     // This component is only enabled for "my player" (i.e. the character belonging to the local client machine).
     // Remote players figures will be moved by a NetworkCharacter, which is also responsible for sending "my player's"
     // location to other computers.
     
     public float speed = 10f;        // The speed at which I run
     public float jumpSpeed = 6f;    // How much power we put into our jump. Change this to jump higher.
     
     // Booking variables
     Vector3 direction = Vector3.zero;    // forward/back & left/right
     float   verticalVelocity = 0;        // up/down
     
     CharacterController cc;
     Animator anim;
     
     // Use this for initialization
     void Start () {
         cc = GetComponent<CharacterController>();
         anim = GetComponent<Animator>();
     }
     
     // Update is called once per frame
     void Update () {
         
         // WASD forward/back & left/right movement is stored in "direction"
         direction = transform.rotation * new Vector3( Input.GetAxis("Horizontal") , 0, Input.GetAxis("Vertical") );
         
         // This ensures that we don't move faster going diagonally
         if(direction.magnitude > 1f) {
             direction = direction.normalized;
         }
         
         // Set our animation "Speed" parameter. This will move us from "idle" to "run" animations,
         // but we could also use this to blend between "walk" and "run" as well.
         anim.SetFloat("Speed", direction.magnitude);
         
         // If we're on the ground and the player wants to jump, set
         // verticalVelocity to a positive number.
         // If you want double-jumping, you'll want some extra code
         // here instead of just checking "cc.isGrounded".
         if(cc.isGrounded && Input.GetButton("Jump")) {
             verticalVelocity = jumpSpeed;
         }
     }
     
     // FixedUpdate is called once per physics loop
     // Do all MOVEMENT and other physics stuff here.
     void FixedUpdate () {
         
         // "direction" is the desired movement direction, based on our player's input
         Vector3 dist = direction * speed * Time.deltaTime;
         
         if(cc.isGrounded && verticalVelocity < 0) {
             // We are currently on the ground and vertical velocity is
             // not positive (i.e. we are not starting a jump).
             
             // Ensure that we aren't playing the jumping animation
             anim.SetBool("Jumping", false);
             
             // Set our vertical velocity to *almost* zero. This ensures that:
             //   a) We don't start falling at warp speed if we fall off a cliff (by being close to zero)
             //   b) cc.isGrounded returns true every frame (by still being slightly negative, as opposed to zero)
             verticalVelocity = Physics.gravity.y * Time.deltaTime;
         }
         else {
             // We are either not grounded, or we have a positive verticalVelocity (i.e. we ARE starting a jump)
             
             // To make sure we don't go into the jump animation while walking down a slope, make sure that
             // verticalVelocity is above some arbitrary threshold before triggering the animation.
             // 75% of "jumpSpeed" seems like a good safe number, but could be a standalone public variable too.
             //
             // Another option would be to do a raycast down and start the jump/fall animation whenever we were
             // more than ___ distance above the ground.
             if(Mathf.Abs(verticalVelocity) > jumpSpeed*0.75f) {
                 anim.SetBool("Jumping", true);
             }
             
             // Apply gravity.
             verticalVelocity += Physics.gravity.y * Time.deltaTime;
         }
         
         // Add our verticalVelocity to our actual movement for this frame
         dist.y = verticalVelocity * Time.deltaTime;
         
         // Apply the movement to our character controller (which handles collisions for us)
         cc.Move( dist );
     }
 }