int led = 12;
int boton = 4;

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  pinMode(boton, INPUT);

}

void loop() {
  // put your main code here, to run repeatedly:
  if(digitalRead(boton)==HIGH){
    digitalWrite(led, HIGH);
  }
  else{
    digitalWrite(led, LOW);
  }
}