volatile int countA = 0;
volatile int countB = 0;
volatile bool flagA = 0;
volatile bool flagB = 0;

void setup() {
attachInterrupt(0, fazaA, CHANGE);
attachInterrupt(1, fazaB, CHANGE);

Serial.begin(9600);
}

void loop() {
Serial.println(countA);
Serial.println(countB);
delay(200);
}

void fazaA(){
  if (flagB == 0){
flagA = 1;
  }
  else{
    flagB = 0;
  }
  countA++;
}

void fazaB(){
  if (flagA){
    countB++;
    flagA = 0;
    Serial.println("Forward");
  }
  else{
    flagB = 1;
    countB--; 
    Serial.println("Backward");
  }
  }