int potpin = A0;
int led1 = 9;
int led2 = 10;
int led3 = 8;
int led4 = 7;
int val = 0;

void setup () {
  pinMode(led1, OUTPUT);
  pinMode(led2, OUTPUT);
  pinMode(led3, OUTPUT);
  pinMode(led4, OUTPUT);
}

void loop () {
  val=analogRead(potpin);
  digitalWrite(led1, HIGH);
  digitalWrite(led2, LOW);
  digitalWrite(led3, HIGH);
  digitalWrite(led4, LOW);
  delay (val);
  digitalWrite(led1, LOW);
  digitalWrite(led2, HIGH);
  digitalWrite(led3, LOW);
  digitalWrite(led4, HIGH);
  delay (val);
  digitalWrite(led1, LOW);
  digitalWrite (led2, LOW);
  digitalWrite (led3, LOW);
  digitalWrite (led4, LOW);
  delay (val);
}