int LED = 4; 
int PB = 16;
bool buttonState = false ; 

void setup() { 
    pinMode(LED, OUTPUT); 
    pinMode(PB, INPUT);
} 

void loop() {
  buttonState = digitalRead(PB);

  if (buttonState == HIGH){
    digitalWrite(LED, HIGH); 
    delay(1000); 
  } 
  else {
    digitalWrite(LED, LOW); 
    delay(1000);
  }

}