const int led = 10;
const int btn = 8;

void setup() {
  // put your setup code here, to run once:
  pinMode(led, OUTPUT);
  pinMode(btn, INPUT_PULLUP);
}

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