#define echo 2
float distance;
void setup() {
  pinMode(echo, INPUT);
  for (int i=3; i<=13 ; i++){
    pinMode(i, OUTPUT);
  }
  Serial.begin(9600);

}

void loop() {
  digitalWrite(3, LOW);
  delayMicroseconds(10);
  digitalWrite(3, HIGH);
  delayMicroseconds(10);
  digitalWrite(3, LOW);
  int dis=pulseIn(echo,HIGH);
  distance=((dis/2)*0.0343);
  Serial.println(distance);
  delay(500);
int n =map(distance ,0 , 400 , 4 , 13);
for(int i=3;i<=n; i++) {
  digitalWrite(i, HIGH);
  delay(1500);
  digitalWrite(i, LOW);
  
}

}