int zero;

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  Serial.println("running");
  zero = analogRead(A0);
}

void loop() {
  // put your main code here, to run repeatedly:
  int x = analogRead(A0) - zero;
  Serial.print("light\t");
  Serial.print(x);
  Serial.print("\n");
}