void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  uint8_t A[3][4] = {
    {0,1},
    {4,5,6},
    {8,9,10}
  };

  uint8_t rows = sizeof(A)/sizeof(A[0]); 
  uint8_t colums = sizeof(A[0])/sizeof(A[0][0]);

  for (int i=0; i<rows; i++){
    for (int j=0; j<colums; j++){
      Serial.print(A[i][j]);
      Serial.print(" ");
    }
    Serial.println();
  }

  while(1);

}