#define VP 36
const byte LED = 18;

void setup() {
  pinMode(LED, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  unsigned int VR = analogRead(VP);
  byte state = map(VR,0,4095,0,4);
  if (state == 1){
    myfunc1();
  }else if (state ==2){
    long x = myfunc2();
    Serial.println(x);
  }else if (state ==3){
    myfunc3(state);
  }else if (state ==4){
    long x = myfunc4(state);
  }else{
    Serial.println("Function is not found !!!");
  }
}
void myfunc1(void){
  digitalWrite(LED, LOW);
  delay(500);
  digitalWrite(LED, HIGH);
  delay(500);
}
long myfunc2(void){
  digitalWrite(LED, LOW);
  delay(500);
  digitalWrite(LED, HIGH);
  delay(500);
  return pow (10,3);
}
void myfunc3(int y){
  int i;
  for(i = 0;i<y;i++){
    Serial.print("i = ");
    Serial.println(i);
    delay(2000);
  }
}
long myfunc4(int y){
  int i = 0;
  while(i<y){
    if((i+y)>2){
      digitalWrite(LED, LOW);
    }else{
      digitalWrite(LED, HIGH);
    }
  i++;
  }
  return pow (i,y);
}