int potpin=15;
int ledpin=5;
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  Serial.begin(9600);
  pinMode(12,INPUT);
  pinMode(21,OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  int val=analogRead(12);
  digitalWrite(21, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(val);                       // wait for a second
  digitalWrite(21, LOW);    // turn the LED off by making the voltage LOW
  delay(val); 
  Serial.println(val);                      // wait for a second
}