int p1=13;
int p2=7;
int p3=8;
void setup() {
  // put your setup code here, to run once:
  pinMode(p1, OUTPUT);
  pinMode(p2, INPUT);
  pinMode(p3, OUTPUT);
}
void loop() {
  // put your main code here, to run repeatedly:
  if(digitalRead(p2)==0)
  {
    digitalWrite(p1, LOW);
    digitalWrite(p3, HIGH);
    delay(500);
  }
  else
  {
    digitalWrite(p1, HIGH);
    digitalWrite(p3, LOW); 
  }
}