const int led = 3;
const int butt = 2;
const int pot = A0;
bool push = 0;
bool status = 0;
int pvalue;
int fvalue;

void setup() {
  pinMode(led, OUTPUT);
  pinMode(butt, INPUT);
  pinMode(pot, INPUT);
  Serial.begin(9600);
}

void loop() {
  pvalue = analogRead(A0);
  fvalue = map(pvalue,0,1023,0,255);
  push = digitalRead(butt);
  if(push > 0){
    status = !status; 
    if(status > 0){
      analogWrite(led,fvalue);
    }
    else{
      analogWrite(led, 0);
    }  
    while (push>0){
      push = digitalRead(butt);
      if (push==0) break;
    }
  }
  if(status > 0){
    analogWrite(led,fvalue);
  }
  else{
    analogWrite(led, 0);
  }
  delay(100);
}