// constants won't change. Used here to set a pin number:
const int ledPin = 7;// the number of the LED pin 13
const int ledPin2 = 8;
const int ledPin3 = 9;
const int button = 2;
// Variables will change:
int ledState = LOW;// ledState used to set the LED
int ledState2 = LOW;
int ledState3 = LOW;
// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long previousMillis = 0; // will store last time LED was updated
unsigned long previousMillis2 = 0;
unsigned long previousMillis3 = 0;
// constants won't change:
const long interval = 2000; // interval at which to blink (milliseconds)
const long interval2 = 500;
const long interval3 = 4000;

void setup() {
  // set the digital pin as output:
  pinMode(ledPin, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
 
}

void loop() {
  // check to see if it's time to blink the LED; that is, if the difference
  // between the current time and last time you blinked the LED is bigger than
  // the interval at which you want to blink the LED.
  unsigned long currentMillis = millis();

  if (currentMillis - previousMillis >= 1000) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    // if the LED is off turn it on and vice-versa:
      if (ledState == LOW) {
      ledState = HIGH;
    } else {
      ledState = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin, ledState);
  }
  if (currentMillis - previousMillis2 >= 500) {
    // save the last time you blinked the LED
    previousMillis2 = currentMillis;

    // if the LED is off turn it on and vice-versa:
     if (ledState2 == LOW) {
      ledState2 = HIGH;
    } else {
      ledState2 = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin2, ledState2);
  }
   if (currentMillis - previousMillis3 >= 1500) {
    // save the last time you blinked the LED
    previousMillis3 = currentMillis;

    // if the LED is off turn it on and vice-versa:
     if (ledState3 == LOW) {
      ledState3 = HIGH;
    } else {
      ledState3 = LOW;
    }

    // set the LED with the ledState of the variable:
    digitalWrite(ledPin3, ledState3);
  }
}