int analogPin = A0;
int ledPin=9;
int inputValue;
int outputValue=0;

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

void loop() {
  // put your main code here, to run repeatedly:
  inputValue=analogRead(analogPin);
  outputValue=map(inputValue,0,1023,0,255);
  analogWrite(ledPin,outputValue);
}