Sol.-

void setup()
{
  pinMode(3,OUTPUT);
  pinMode(A0,INPUT);
  Serial.begin(9600);
}
void loop()
{
  int read =analogRead(A0);
  int vout = (read/1024.0)*5000;
  int celsius=vout/10-49;
  Serial.print("Reading is ");
  Serial.println(celsius);
  if(celsius>30)
  {
    digitalWrite(3,1);
  }
  else
  {
    digitalWrite(3,0);
  }
}

Explain : We can use temperature sensor TMP36 in this because LM35 is not available. 
		We attach a bulb so when temperature increase by 30 degree celsius bulb on.
		For LM35 use :
		  int read =analogRead(A0);
  		int vout = read*4.88;
  		int celsius=vout/10;