#define led1 13
#define led2 12
#define led3 11
#define led4 10
#define interruptPin1 3
#define interruptPin2 2
volatile int num = 100;
///volatile byte state = 0;

void setup() {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
  pinMode(interruptPin1, INPUT_PULLUP);
  pinMode(interruptPin2, INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(interruptPin1), increment, FALLING);
  attachInterrupt(digitalPinToInterrupt(interruptPin2), decrement, FALLING);
  Serial.begin(9600);



}

void loop() {

  Serial.println(num);
  digitalWrite(led1, HIGH);
  delay(num);
  digitalWrite(led2, HIGH);
  delay(num);
  digitalWrite(led3, HIGH);
  delay(num);
  digitalWrite(led4, HIGH);
  delay(num);
  
  digitalWrite(led1, LOW);
  digitalWrite(led2, LOW);
  digitalWrite(led3, LOW);
  digitalWrite(led4, LOW);
  delay(num);

}
void increment() {

  (num < 2000) ? num+= 500: num = 100;

  digitalWrite(led1, num);
  digitalWrite(led2, num);
  digitalWrite(led3, num);
  digitalWrite(led4, num);

}

void decrement() {
  (num>100)? num-=500:num=2000;
  digitalWrite(led1, num);
  digitalWrite(led2, num);
  digitalWrite(led3, num);
  digitalWrite(led4, num);


}