int pA = 12;
int lA = 11;
int pB = 9;
int lB = 8;
int m1 = 3;
int m2 = 2;
int tm = 3000;
bool planta = 1;

void setup() {
  // put your setup code here, to run once:
pinMode(pA, INPUT);
pinMode(lA, OUTPUT);
pinMode(pB, INPUT);
pinMode(lB, OUTPUT);
pinMode(m1, OUTPUT);
pinMode(m2, OUTPUT);
digitalWrite(lA,1);
}

void loop() {
  // put your main code here, to run repeatedly:
bool vpA = digitalRead(pA);
bool vpB = digitalRead(pB);

if (planta==1 && vpB==1){
  digitalWrite(lA,0);
  digitalWrite(m2,0);
  digitalWrite(m1,1);
  delay(tm);
  digitalWrite(m1,0);
  digitalWrite(lB,1);
  planta = 0;
}
if (planta==0 && vpA==1){
  digitalWrite(lB,0);
  digitalWrite(m1,0);
  digitalWrite(m2,1);
  delay(tm);
  digitalWrite(m2,0);
  digitalWrite(lA,1);
  planta = 1;
}

}