float U = A0 ;
float temp ;
int i = 0 ;
float tempamb =  ;

void setup() {
  pinMode (2, OUTPUT) ;
  Serial.begin (9600) ;

}

void loop() {
  temp =  ;
  if (temp > tempamb + 5) {
    digitalWrite (2,HIGH) ; }    
    else { 
      digitalWrite (2, LOW) ;
      }
  if (temp > tempamb + 10) {
      digitalWrite (3,HIGH) ; }    
    else { 
      digitalWrite (3, LOW) ;
  }
if (temp > tempamb + 15) {
      digitalWrite (4,HIGH) ; }    
    else { 
      digitalWrite (4, LOW) ;
  }
if (temp > tempamb + 20) {
      digitalWrite (5,HIGH) ; }    
    else { 
      digitalWrite (5, LOW) ;
  }
}