void IST(String time){
  int hour = atoi(time.substring(0,2).c_str());   
  int minute = atoi(time.substring(2,4).c_str());
  int second = atoi(time.substring(4,9).c_str());  
  
  int addHour = 5;    
  int addMinute = 30; 
  
  int newHour = (hour + addHour) % 24;
  int newMinute = (minute + addMinute) % 60;
  int newSecond = second;
  
  if (newMinute < minute) {
    newHour = (newHour + 1) % 24;
  }
  
  String IST=String(newHour)+":"+String(newMinute)+":"+String(newSecond);
//  Serial.print("Indian Standard Time: ");
//  Serial.print(newHour);
//  Serial.print(":");
//  Serial.print(newMinute);
//  Serial.print(":");
//  Serial.println(newSecond);
}