int switchmode=0;
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(18, OUTPUT);
  pinMode(12,INPUT);
}

// the loop function runs over and over again forever
void loop() {
  switchmode= digitalRead(12);
  if(switchmode==HIGH)
  {
  digitalWrite(18, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(18, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);
  }
  else if(switchmode==LOW){
    digitalWrite(18, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);
  }                  // wait for a second
}