int pins[3]{2, 3, 4};
int i;

void setup() {
//[]
Serial.begin(9600);
Serial.println("BEGIN");
Serial.println();

for (i=2; i<5; i++) {
  pinMode(pins[i], OUTPUT);
}

}

void loop() {

if (analogRead(A0) < 250) {
  digitalWrite(pins[0], HIGH);
  digitalWrite(pins[1], LOW);
  digitalWrite(pins[2], LOW);
}

if (analogRead(A0) > 250 && analogRead(A0) < 800) {
  digitalWrite(pins[0], LOW);
  digitalWrite(pins[1], HIGH);
  digitalWrite(pins[2], LOW);
}

if (analogRead(A0) > 800) {
  digitalWrite(pins[0], LOW);
  digitalWrite(pins[1], LOW);
  digitalWrite(pins[2], HIGH);
}

}