int ledRed = 1;
int ledBlue = 2;
int delayTime = 1000;

void setup() {
  pinMode(ledRed, OUTPUT);
  pinMode(ledBlue, OUTPUT);
}

void loop() {
  digitalWrite(ledRed, HIGH);
  delay(delayTime);
  digitalWrite(ledRed, LOW);
  delay(delayTime);
  digitalWrite(ledBlue, HIGH);
  delay(delayTime);
  digitalWrite(ledBlue, LOW);
  delay(delayTime);
  
  if (delayTime<=0){
    delay(3000);
    delayTime = 1000;
  }
  else {
    delayTime = delayTime-100;
  }
}