#include <Arduino.h>
#define LED 5
#define POT A0

int val = 0;

void setup()
{
  // put your setup code here, to run once:
  pinMode(LED, OUTPUT);
}

void loop()
{
  // put your main code here, to run repeatedly:
  val = analogRead(POT);
  val = map(val, 0, 1023, 0, 255);
  analogWrite(LED, val);
}