void loop() {
    // digitalWrite(ledPin, HIGH);
    // delay(1000);
    
    // digitalWrite(ledPin, LOW);
    // delay(1000);
    
    //exercise 3
    analogWrite(ledPin, 150);

    
    for(int i=0; i<=5; i++){
        digitalWrite(ledPin, HIGH);
        delay(500);
        digitalWrite(ledPin, LOW);
        delay(500);
        if(i==5){
            delay(3000);
            i=0;
        }
    }

}