int led = 8;
int btn = 2;
void setup() {
  // put your setup code here, to run once:
pinMode(led , OUTPUT);
pinMode(btn , INPUT);
}

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