const int VL = 4;     // the number of the swich pin, VL stands for logic voltage
const int PR = 2;      // the number of the LED pin, PR stands for red probe
const int PG = 3;      // the number of the LED pin, PG stand for green probe
const int VP = A0;    // select the input pin for the potentiometer
// variables will change:
// int SwitchState = 0;         // give a name for the switch state variable
int PotValue = 0;  // variable to store the value coming from the sensor
//declares the inputs and outputs of the circuit
void setup() {
  pinMode(A0, INPUT);
//  pinMode(VL, INPUT);
  pinMode(PR, OUTPUT);
  pinMode(PG, OUTPUT);
}

// your code written here keeps running until eternity
void loop() {
  //reads from the switch to determine which LED should be on
  // SwitchState = digitalRead(VL);
  //reads from the pot pin and assign it to the PotValue
  PotValue = analogRead(VP);
  //When the pot reading is less than 250, both the red and green LEDS are turned off
  if (PotValue < 250)
  {
     digitalWrite(PR, 0);   
     digitalWrite(PG, 1);
  }
  
  //When the pot reading is less than 500 and greater than 250, the red LED is turned off and the green LED is turned on
  else if (PotValue < 500)
  {
     digitalWrite(PR, 0);   
     digitalWrite(PG, 0);
  }
  
  //When the pot reading is less than 750 and greater than 500,  both the red and green LEDS are turned on
  else if (PotValue < 750)
  {
     digitalWrite(PR, 1);   
     digitalWrite(PG, 0);
  }
  
  //When the pot reading is greater than 750, the red LED is turned on and the green LED is turned off
  else 
  {
     digitalWrite(PR, 1);   
     digitalWrite(PG, 1);
  }
}