#define A0 0
int inputValue = 0;
void setup() 
{
 pinMode(13, OUTPUT);
 Serial.begin(9600);
 }
void loop() 
{
  digitalWrite(13, HIGH);
  delay(inputValue);
  digitalWrite(13, LOW);
  delay(inputValue);
  inputValue = analogRead(A0);
  Serial.println(inputValue);
  }