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

void loop() {
  // put your main code here, to run repeatedly:
  int input = analogRead(A0);
  int output = map(input,0,1023,-1999,9999);
  Serial.print(input);
  Serial.print(" value was mapped to ");
  Serial.println(output);
  delay(100);
}