void setup() {
  Serial.begin(115200);
  pinMode(16, OUTPUT);
  pinMode(5, INPUT);
}

void loop() {
  int a=digitalRead(5);
  if(a==1)
  {
    digitalWrite(16, HIGH);
    Serial.println("switch is on");
  }
  if(a==0)
  {
    digitalWrite(16, LOW);
    Serial.println("switch is off");
  }
}