void setup() {
  // put your setup code here, to run once:
  pinMode(3,OUTPUT);
  pinMode(4,INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
 // bool But = digitalRead(4);
 // if (But) 
 // {
 //   digitalWrite(3, HIGH);
 // }
 // else
 // {
 //   digitalWrite(3,LOW);
 // }
  digitalWrite(4, HIGH);
  delay(1000);
  digitalWrite(4,LOW);
  delay(1000);
}