int led=5;
int val;
void setup() {
  // put your setup code here, to run once:
pinMode(led,HIGH);
Serial.begin(9600);

}

void loop() {
  // put your main code here, to run repeatedly:
if(Serial.available()>0)
{
  val=Serial.read();
}
if(val==1)
{
  digitalWrite(led,HIGH);
}
else if (val==0)
{
  digitalWrite(led,LOW);
}
else
{
Serial.print("invalid signal");
}
}