int  relay= 13;                
int sensor = 2;                      
int val = 0;                 
void setup() {
  pinMode(relay, OUTPUT);      
  pinMode(sensor, INPUT);         
}
void loop(){
  val = digitalRead(sensor);   
  if (val == HIGH) {           
    digitalWrite(relay, HIGH);    
} 
  else {
      digitalWrite(relay, LOW); 
                  
      
            
    }
}