Increase the number just when the button is pressed

I make the alphabets select screen and i want to detect just those alphabets those are selected by user but i also have the unselect button feature so i want the functionality that if user press the button number count increase but when i again press the button to unselect the count number not increase. Here is my Select Button functionality : public bool defaultColor = true; Color32 transparentColor = new Color32(255, 255, 225, 150); Color32 originalColor = new Color32(255, 255, 225, 250);

 public GameObject image;

 public void TransparencyChange()
 {
     if (defaultColor == true)
     {
         image.GetComponent<Image>().color = transparentColor;
         defaultColor = false;
     }
     else if (defaultColor != true)
     {
         image.GetComponent<Image>().color = originalColor;
         defaultColor = true;
     }
 }

And Here is the Increase count number functionality which is attached to on click event of button: private Text count; private int countAmount;

 public void Start()
 {
     countAmount = 0;
     count = GetComponent<Text>();
 }
 // Update is called once per frame
 void Update()
 {
     count.text = countAmount.ToString();
 }
 public void AddScore()
 {
     countAmount += 1;
 }

}