const int analogInPin = A0;

int sensorValue = 0;
int timer = 0;

void setup(){
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
}

void loop(){
  sensorValue = analogRead(analogInPin);

  timer = map(sensorValue, 0, 1023, 10, 50);
  digitalWrite(12, HIGH);
  delay(timer);
  digitalWrite(12, LOW);
  delay(timer);
  digitalWrite(12, HIGH);
  delay(timer);
  digitalWrite(12, LOW);

  digitalWrite(11, HIGH);
  delay(timer);
  digitalWrite(11, LOW);
  delay(timer);
  digitalWrite(11, HIGH);
  delay(timer);
  digitalWrite(11, LOW);

  digitalWrite(12, HIGH);
  delay(timer);
  digitalWrite(12, LOW);
  delay(timer);
  digitalWrite(11, HIGH);
  delay(timer);
  digitalWrite(11, LOW);
}