int temp , m = 10, sum, r = 10,flag=0,temp2,n; String input; const int ledPin = 13; void setup() { Serial.begin(9600); Serial.setTimeout(10); pinMode(ledPin,OUTPUT); } void loop() { while (Serial.available()==0){} input = Serial.readStringUntil('\n'); Serial.println("The value of n " + input); n = input.toInt(); temp = n; temp2 = n; while (temp2 <= temp && flag<=1) { while (n >= m) n /= 10; m*=10; temp2 = n; Serial.println(n+" "+m); sum=0; while (n > 0) { r = n % 10; sum = (sum * 10) + r; n = n / 10; } if (temp2 == sum) { Serial.println("1"); digitalWrite(ledPin,HIGH); } else { Serial.println("0"); digitalWrite(ledPin,LOW); } n=temp; if(temp2==temp) { flag++; } } }