void setup() {
  // put your setup code here, to run once:
  volatile char *dirf = 0x30;
  *dirf = 0x03;
  volatile char *dirk = 0x107;
  *dirf = 0x03;
  volatile char *outk = 0x108;
  volatile char *outf = 0x31;
  while(1){
    volatile int i = 9;
    //PULL UP
    *outf = 0x01; // If A0 is 1, LED is ON, as we know that potential drop from high to low,
                  // Here, as we are mentioning "1", it will be 5V --> 5V. So, the current
                  // prefer to use least resistance path and because of this LED turns ON
    delay(1000);
    while(i){
      *outf = 0x02;
      delay(1000);
      *outf = 0x01;
      delay(1000);
      i--;
    }
    *outf = 0x00;
    delay(10);

    // PULL DOWN
    *outk = 0x01;
    delay(1000);
    i = 9;
    while(i){
      *outk = 0x02;
      delay(1000);
      *outk = 0x01;
      delay(1000);
      i--;
    }
    *outk = 0x00;
    delay(10);
  }
}

void loop() {
  // put your main code here, to run repeatedly:

}