const int sensorPin = A0;
const int motorPin1 = 2;
const int motorPin2 = 3;
const int motorPin3 = 4;
const int motorPin4 = 5;

void setup() {
  pinMode(sensorPin, INPUT);
  pinMode(motorPin1, INPUT);
  pinMode(motorPin2, INPUT);
  pinMode(motorPin3, INPUT);
  pinMode(motorPin4, INPUT);
}

void loop() {
  int sensorValue = analogRead(sensorPin);

  if (sensorValue > 100 && sensorValue <= 300) {
    // to move motor 1
    digitalWrite(motorPin1, HIGH);
    digitalWrite(motorPin2, LOW);
    digitalWrite(motorPin3, LOW);
    digitalWrite(motorPin4, LOW);
  } else if (sensorValue > 300 && sensorValue <= 600) {
    // to move motor 2
    digitalWrite(motorPin1, LOW);
    digitalWrite(motorPin2, HIGH);
    digitalWrite(motorPin3, LOW);
    digitalWrite(motorPin4, LOW);
  } else if (sensorValue > 600 && sensorValue <= 800) {
    // to move motor 3
    digitalWrite(motorPin1, LOW);
    digitalWrite(motorPin2, LOW);
    digitalWrite(motorPin3, HIGH);
    digitalWrite(motorPin4, LOW);
  } else if (sensorValue > 800) {
    // to move motor 4
    digitalWrite(motorPin1, LOW);
    digitalWrite(motorPin2, LOW);
    digitalWrite(motorPin3, LOW);
    digitalWrite(motorPin4, HIGH);
  } else {
    // no movement when values are out of expected range 
    digitalWrite(motorPin1, LOW);
    digitalWrite(motorPin2, LOW);
    digitalWrite(motorPin3, LOW);
    digitalWrite(motorPin4, LOW);
  }
}