void setup() {
  pinMode(A0, INPUT);
  pinMode(13, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, OUTPUT);
  pinMode(10, OUTPUT);
  pinMode(9, OUTPUT);
  pinMode(8, OUTPUT);
  pinMode(7, OUTPUT);
}

void loop() {
  int A = analogRead(A0);
  if (A >= 20) {
    digitalWrite(13, HIGH);
    if (A >= 100) {
      digitalWrite(12, HIGH);
      if (A >= 150) {
        digitalWrite(11, HIGH);
        if (A >= 200) {
          digitalWrite(10, HIGH);
          if (A >= 250) {
            digitalWrite(9, HIGH);
            if (A >= 300) {
              digitalWrite(8, HIGH);
              if (A >= 350) {
                digitalWrite(7, HIGH);
    
    }
    else
    {
    digitalWrite(7, LOW);
    }
    }
    else
    {
    digitalWrite(8, LOW);
    }
    }
    else
    {
    digitalWrite(9, LOW);
    }
    }
    else
    {
    digitalWrite(10, LOW);
    }
    }
    else
    {
    digitalWrite(11, LOW);
    }
    {
    digitalWrite(12, LOW);
    }
    }
  }
  else
  {
    digitalWrite(13, LOW);
    digitalWrite(12, LOW);
    digitalWrite(11, LOW);
    digitalWrite(10, LOW);
    digitalWrite(9, LOW);
    digitalWrite(8, LOW);
    digitalWrite(7, LOW);
  };
}