#define  red 13
int b;
void setup()
 {
  Serial.begin(9600);
  pinMode(red, OUTPUT);
  Serial.println("enter the signal value");
  b=Serial.read();

}
void loop() 
{
int a = Serial.read() - '0';
    if (a == 1) 
    {
      digitalWrite(red, HIGH);                 
    }
    if(a == 0)
    {
      digitalWrite(red, LOW);
    }


    }