int led=12;
int sw=4;

void setup() {
  // put your setup code here, to run once:
pinMode(led,OUTPUT);
pinMode(sw,INPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
int b=digitalRead(sw);
digitalWrite(led,b);
Serial.println(b);
delay(1); //delay for stability
}