int A = 6, B = 5, C = 4, D = 3;
void setup() {
  Serial.begin(9600);

  D = C;
  C = B;
  B = A;

  Serial.print(" A = ");
  Serial.print(A);

  Serial.print(" B = ");
  Serial.print(B);

  Serial.print(" C = ");
  Serial.print(C);

  Serial.print(" D = ");
  Serial.print(D);
}

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

}