int cs = HIGH, ps = HIGH, j = 0;
const float GAMMA = 0.7;
const float RL10 = 50;
void setup() {
  pinMode(A0, INPUT);
  pinMode(5, OUTPUT);
  pinMode(12, INPUT_PULLUP);
  Serial.begin(9600);
}

void loop() {
  cs = digitalRead(12);
  int i = analogRead(A0);
  float voltage = i / 1024. * 5;
  float resistance = 2000 * voltage / (1 - voltage / 5);
  float lux = pow(RL10 * 1e3 * pow(10, GAMMA) / resistance, (1 / GAMMA));

  if(cs == LOW && cs != ps)
    j++;
  if(j == 2)
    j = 0;
  if(j == 1){
    if(lux < 10)
      digitalWrite(5, HIGH);
    else 
      digitalWrite(5, LOW);
  }
  
  if (j == 0)
    digitalWrite(5, LOW);
  Serial.println(i);
  ps = cs;
}