int potValue;
int mappedpotValue;
void setup() {
  // put your setup code here, to run once:
  pinMode(3,OUTPUT);
  pinMode(A0,INPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
  // Sensor Read
    potValue= analogRead(A0); // 0-1023
  // Mapping
    mappedpotValue=map(potValue,0,1023,0,255);
  // Analog Write
    analogWrite(3,mappedpotValue);
}