Manabar Pause Limit

I"m trying to get that the player can no longer pause when the ManaBar is empty. But I just can't seem to get a script in my mind for it... Here's the Pausing script:

 using UnityEngine;
 using System.Collections;
 
 public class Freeze : MonoBehaviour {
     public int p = 0;
     private GameObject target;
     public void Start() {
     target = GameObject.FindGameObjectWithTag("player");     
 }
     public void Update () {
     AddjustCurrentfreeze(0);
     }
     public void AddjustCurrentfreeze(int adj) {
         p += adj;
         
     if (Input.GetKeyDown(KeyCode.P))
     {
     if (p == 0)
     {
     Time.timeScale=0;
     Screen.showCursor = true;
     Screen.lockCursor = false;            
     p = 1;
     PlayerManaBar eh = (PlayerManaBar)target.GetComponent("PlayerManaBar");
     eh.AddjustCurrentMana(-100);    
     }
     else
     {
     Time.timeScale=1.0f;
     p=0;
   
     }
     }
 
 }
 }

Here's the ManaBar script :

  using UnityEngine;
     using System.Collections;
      
     public class PlayerManaBar : MonoBehaviour {
      public GameObject target;
     GUIStyle style = new GUIStyle();
     Texture2D texture;
     Color yeColor = Color.yellow;
     Color cyanColor = Color.cyan;
     private int curMana = 1000;
     private int maxMana = 1000; 
     void Start()
     {
     texture = new Texture2D(1, 1);
     texture.SetPixel(1, 1, cyanColor);
     }
      
    void Update()
     {
         AddjustCurrentMana(0);
     }
     public void AddjustCurrentMana(int adj) {
         curMana += adj;
             
     if(curMana < 0)
     {     
     curMana = 0;
     }
     
     if(curMana > maxMana)
     {
     curMana = maxMana;
     }
         
     if(maxMana < 1)
     {
     maxMana = 1;
     }
 if (curMana <= 1000)
 {
 texture.SetPixel(1, 1, cyanColor);
 }
 
     }
  
 public void OnGUI()
 {
  
 texture.Apply();
  
 style.normal.background = texture;
     GUI.Box(new Rect(10, 40, curMana, 20), new GUIContent(""), style);
     GUI.Box(new Rect(10, 40, 1000, 20), "");    
     
 }
 }