byte LED = 18;
byte sw = 25;
byte VP=36;

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

void loop() {
  unsigned int vr = analogRead(VP);
  unsigned int vmap = map (vr,0,4095,0,255);
  Serial.print("VR =");
  Serial.println(vr);
  delay(1000);
  Serial.print("Vmap =");
  Serial.println(vmap);
  delay(1000);
}