#define relay 13
#define RC_pin A0


void setup() {

  pinMode(RC_pin,INPUT);
  pinMode(relay, OUTPUT);

}

void loop()
{
int RC_value =analogRead(RC_pin); 
    if(RC_value>=200)
{

   digitalWrite(relay, HIGH);

}
else  
   {     
  
       digitalWrite(relay, LOW);
    }
}