int LDR =0;
void setup() {
 Serial.begin(9600);
pinMode(A0, INPUT);
pinMode(6, OUTPUT);
pinMode(5, OUTPUT);
pinMode(4, OUTPUT);
pinMode(3, OUTPUT);
pinMode(2, OUTPUT);
pinMode(1, OUTPUT);
}
void loop() {
int LDR = analogRead(A0);
float kilometres = 1/(log(1/(1023./LDR-1))/3950+1.0/298.15)-273.15;
Serial.print("Speed: ");
Serial.print(kilometres);
Serial.print("km/h ");
delay(500);
if (kilometres >= 0 && kilometres <20){
  digitalWrite(2, LOW);
  digitalWrite(3, LOW);
  digitalWrite(4, LOW);
  digitalWrite(5, LOW);
  digitalWrite(6, HIGH);
  digitalWrite(7, HIGH);
}
else if (kilometres >= 20 && kilometres <30){
  digitalWrite(2, LOW);
  digitalWrite(3, LOW);
  digitalWrite(4, HIGH);
  digitalWrite(5, HIGH);
  digitalWrite(6, LOW);
  digitalWrite(7, LOW);
}
else if (kilometres >= 30 && kilometres <50){
  digitalWrite(2, HIGH);
  digitalWrite(3, HIGH);
  digitalWrite(4, LOW);
  digitalWrite(5, LOW);
  digitalWrite(6, LOW);
  digitalWrite(7, LOW);
}
else if (kilometres >= 50 && kilometres <60){
  digitalWrite(2, LOW);
  digitalWrite(3, LOW);
  digitalWrite(4, HIGH);
  digitalWrite(5, HIGH);
  digitalWrite(6, LOW);
  digitalWrite(7, LOW);
}
else if (kilometres >= 60){
  digitalWrite(2, LOW);
  digitalWrite(3, LOW);
  digitalWrite(4, LOW);
  digitalWrite(5, LOW);
  digitalWrite(6, HIGH);
  digitalWrite(7, HIGH);
}

}