void setup()  
{
  pinMode(3, OUTPUT);
  pinMode(A0, INPUT);
  Serial.begin(9600);
  // put your setup code here, to run once:

}

void loop() 
{
  int x=analogRead(A0);
  Serial.print("x:");
  Serial.println(x);
  int y=map(x,0,1023,0,255);
  Serial.print("y:");
  Serial.println(y);
  analogWrite(3,y);
  delay(1000);
  // put your main code here, to run repeatedly:

}