#define L0 digitalWrite(2,0);
#define L1 digitalWrite(2,1);
#define M0 digitalWrite(4,0);
#define M1 digitalWrite(4,1);

void setup(){
  pinMode(3, INPUT);
  pinMode(5, INPUT);
  pinMode(2, OUTPUT);
  pinMode(4, OUTPUT);
}

void loop(){
  byte A = digitalRead(3);
  byte B = digitalRead(5);
  if(!A && !B){L0;M0;}
  if(!A && B) {L1;M1;delay(500);L0;M0;delay(500);}
  if(A && !B) {L1;M0;}
  if(A && B)  {L0;M1;}
}