int button_value;

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

  pinMode(10, INPUT);
  pinMode(3, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  button_value = digitalRead(10);

  if (button_value == HIGH) {
    digitalWrite(3, HIGH);
    Serial.println("led on");
  }
  else if (button_value == LOW) {
    digitalWrite(3, LOW);
    Serial.println("led off");
  }
}