int led = 8;
int btn = 7;



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


}

void loop() {
  // put your main code here, to run repeatedly:
  if (digitalRead(btn)==0){
       digitalWrite(led,HIGH);
  }
  else{
    digitalWrite(led,LOW);
  }
}