int led1 = 6;
int led2 = 7;
int potpin = 0;
int val = 0;

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

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