int a;

volatile bool

void setup() {
  pinMode(3, OUTPUT);  
  pinMode(4, OUTPUT);
  pinMode(2, INPUT_PULLUP);

  Serial.begin(9600);
  attachInterrupt(digitalPinToInterrupt(2),reset,FALLING);
  Serial.println("Zadaj:");
}

void loop() {
  Serial.println("do akej strany?");
  
  while (!Serial.available()) {
  }
  
  String kde = Serial.readStringUntil('\n');
  if (kde == "l") {
    digitalWrite(4, LOW);  
    Serial.println("lava");
  } else if (kde == "p") {
    Serial.println("prava");
    digitalWrite(4, HIGH);   

  }
  Serial.read();
  Serial.println("kolko krokov?");
  while (!Serial.available()) {
  }
  int a = Serial.parseInt();
  Serial.println(a);
  for (int i = 0; i < a; i++) {
    step();
  }
  Serial.read();
  Serial.read();
}

void step() {
  digitalWrite(3, HIGH);
  delay(6);
  digitalWrite(3, LOW);
  delay(6);
}
void reset(){
  a = 0;
}