void setup() {
 Serial.begin(9600);
pinMode(2, OUTPUT);
pinMode(5, INPUT);
 }
void loop() {
 int ldr=analogRead(A0);
 if(ldr>100){
  analogWrite(2, ldr);
  Serial.println(ldr);
  delay(200);
 }
 else {
  analogWrite(2,0);
   delay(500);
 }
 
}