Simple Program counts OnGUI() If(Button)else(Anywhere but button) Score twice

Hey guys,

I'm really confused about how this code is working in my Unity project. It's a program that's generating randomly placed buttons, and the idea is that your score improves by 1 if you click them before they disappear, and decreases by 1 if you click anywhere else. However, this code is making clicks on the buttons decrease score by 1 and clicks outside the buttons decrease score by 2.

I'd also prefer the score to be calculated on Input.GetMouseButtonDown(0), but I have to use Input.GetMouseButtonUp(0) in order to get the score to synchronize correctly. The scene is extremely simple, with just a main camera, and empty game object with this code attached:

 using UnityEngine;
 using System.Collections;
 
 public class Button : MonoBehaviour
 {
     public GameObject button;
     public float score;
     public float a, b, c, d;
     public bool pressed;
 
     public float delay = .5f;
 
 
     private int width = Screen.width;
     private int height = Screen.height;
 
 
 
     // Use this for initialization
     void Start()
     {
 
     }
     void OnGUI()
     {
 
         if (GUI.Button(new Rect(0, 0, 250, 250), "" + score as string))
         {
             score += 1;
         }
 
         else if (pressed)
         {
             score -= 1;
         }
 
         if (GUI.Button(new Rect(a, b, c, d), "Click me!"))
         {
             score += 1;
         }
 
 
     }
     // Update is called once per frame
     void Update()
     {
         pressed = Input.GetMouseButton(0);
         delay -= Time.deltaTime;
         if (delay < 0)
         {
             a = Random.Range(0, width);
             b = Random.Range(0, height);
             c = Random.Range(0, width);
             d = Random.Range(0, height);
             delay = 0.5f;
         }
 
 
     }
   
     }