my mobile button keeps pressing on its own instead of 1 tap

when user taps 1 touch screen it should move once but when I touch and hold the screen down it keep moving a lot

I just want the 1 tap 1 move feature for the touch button not 1 tap and hold and keeps moving

so if player taps 1once and holds on that 1 tap it will only move once

at the moment this code keeps jumping on tap hold down

please help

android game 2d game

 using UnityEngine;
 using System.Collections;
 
 public class Toucht : MonoBehaviour 
 {
 
         public float upForce;          
         public float downForce;
         public float forwardSpeed;       
         public bool isDead = false;      
 
         Animator anim;                  
         bool flap = false;               
         void Start()
         {
             anim = GetComponent<Animator> ();
             GetComponent<Rigidbody2D>().velocity = new Vector2 (forwardSpeed, 0);
         }
         void Update()
         {
             if (isDead)
                 return;
         Touch myTouch = Input.GetTouch(0);
 
             Touch[] myTouches = Input.touches;
             for(int i = 0; i < Input.touchCount; i++)
 
                 flap = true;
         }
         void FixedUpdate()
         {
             if (flap)
             {
                 flap = false;
                 anim.SetTrigger ("Flap");
                 GetComponent<Rigidbody2D> ().velocity = new Vector2 (GetComponent<Rigidbody2D> ().velocity.x, 0);
                 GetComponent<Rigidbody2D> ().AddForce (new Vector2 (0, upForce));
             }
             if (Input.GetKeyDown("t"))
             {
                 GetComponent<Rigidbody2D>().velocity = new Vector2(GetComponent<Rigidbody2D>().velocity.x, 0);
                 GetComponent<Rigidbody2D> ().AddForce (new Vector2 (-0, downForce));
             }
         }
         int hit = 0; 
         void OnCollisionEnter2D(Collision2D other)
         {
             if(other.gameObject.tag == "Wall")
             {
                 hit++;
                 if(hit >= 25)
                     Destroy(gameObject);
             }
             if(other.gameObject.tag == "Wall")
             {
                 GetComponent<AudioSource>().Play();
             }
 
         }
     }