String input = "";
char inChar = -1;
int pin13 = 13;
void setup() {
  pinMode(pin13,OUTPUT);
  digitalWrite(pin13,HIGH);
  Serial.begin(9600);
}
void loop() {
   while (Serial.available() > 0){
    inChar = Serial.read();
    if(inChar=='1'||inChar=='0'){
      Serial.println("Character " + inChar);
      input.concat(inChar);
      Serial.println("String " + input);
      if (isPalindrome(input))
        digitalWrite(pin13,HIGH);
      else
        digitalWrite(pin13,LOW);
    }
   }
}

 boolean isPalindrome(String original){
    String reverse = ""; // Objects of String class;
    int length = original.length();
    for ( int i = length - 1; i >= 0; i-- )
       reverse = reverse + original.charAt(i);
    if (original.equals(reverse))
       return true;
    else
       return false;
 }