int ledPin=13;
int button=3;

void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  pinMode(button, INPUT);
}

void loop()
{
    if (digitalRead(button) == HIGH)
    {
        digitalWrite(ledPin, HIGH);
    }
    else
    {
        digitalWrite(ledPin, LOW);
    }
}