#define PA0 10
#define PA1 11
#define PA2 12
#define PA3 13
#define PB0 6
#define PB1 7
#define PB2 8
#define PB3 9
#define LENGTH 4
const byte PORTSA[LENGTH] = {PA0,PA1,PA2,PA3};
const byte PORTSB[LENGTH] = {PB0,PB1,PB2,PB3};
byte num1[LENGTH];
byte num2[LENGTH];

// = {0,0,0,0};

void setup() {
  Serial.begin(9600);

  /* Setup ports for input a */
  for (int i = 0; i < LENGTH; i++)
    pinMode(PORTSA[i], OUTPUT);

  /* Setup ports for input b */
  for (int i = 0; i < LENGTH; i++)
    pinMode(PORTSB[i], OUTPUT);
}

void loop() {
  digitalWrite(PB0, LOW);
  digitalWrite(PB1, HIGH);
}