//constants won't change. They're used here to set pin numbers:
const int buttonPin = 4;     // the number of the pushbutton pin
const int ledPin =  13;      // the number of the LED pin

// variables will change:
boolean flag = true;
int buttonState = 0;         // variable for reading the pushbutton status
int distance = 0;

void setup() {

pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
pinMode(8, OUTPUT); //YELLOW
pinMode(9, OUTPUT); //OREN

digitalWrite(buttonPin, LOW);
digitalWrite(8, HIGH);
digitalWrite(9, HIGH);
}

void loop() {

buttonState = digitalRead(buttonPin);// read the state of the pushbutton

if (digitalRead(buttonPin) == LOW) {    // if pushbutton is pressed,
buttonState is HIGH:

digitalWrite(ledPin, HIGH);
digitalWrite(8, LOW);                 //LOW=FORWARD DIRECTION
digitalWrite(9, HIGH);               //9 = MOTOR ON/OFF
delayMicroseconds(100);
digitalWrite(9, LOW);
delayMicroseconds(100);
distance++;

if(distance > 21000){
 distance = 0;
delay (3000);
reverse();
}

}

if (digitalRead(buttonPin) == HIGH){
// turn LED off:
digitalWrite(ledPin, LOW);
digitalWrite(8, LOW); //LOW=FORWARD DIRECTION
digitalWrite(9, LOW); //9 = MOTOR ON/OFF
delayMicroseconds(100);
digitalWrite(9, LOW);
delayMicroseconds(100);


}
}

void reverse(){

digitalWrite(8,HIGH);

digitalWrite(9,HIGH);
delayMicroseconds(100);
digitalWrite(9,LOW);
delayMicroseconds(100);
distance++;

 if(distance > 21000){
 distance = 0;
 delay (3000);
 return;
 }

 reverse();

 }