void setup() {
  Serial.begin (9600); 
  pinMode (5, OUTPUT);
  pinMode (6, OUTPUT);
  pinMode (7, OUTPUT);
}

void loop() {
 int vr = analogRead (A0);
 int mapvr = map(vr,0, 1023,0,300);
Serial.println(mapvr);

if (mapvr < 100) {
  digitalWrite(5, HIGH); 
  digitalWrite(6, LOW); 
  digitalWrite(7, LOW);
}else if(mapvr < 200){
  digitalWrite(5, HIGH); 
  digitalWrite(6, HIGH); 
  digitalWrite(7, LOW); 
}else if(mapvr < 300){
digitalWrite(5, HIGH); 
digitalWrite(6, HIGH); 
digitalWrite(7, HIGH);
}

}