int LED = 13;
int BUTTON = 3；
int val;
void setup()
{
  // put your setup code here, to run once:
    pinMode(LED,OUTPUT);
    pinMode(BUTTON,INPUT);
}
void loop()
{
  // put your main code here, to run repeatedly:
    val = digitalRead(BUTTON);
    if(val == HIGH)
    {
        digitalWrite(LED,HIGH);
    }
    else
    {
        digitalWrite(LED,LOW);
    }
}