void setup() 
{
  serial. begin(9600);
  pinMode(A0,INPUT);
  pinMode(9, OUTPUT) ;
}

void loop() {
int a=analogREAD(A0) ;
int pwn=map(a, 0, 1024, 0 , 255);
serial. print1n(a) ;
analogwrite(9,pwm);
delay(50);
}