#include <avr/io.h>
#include <util/delay.h>

void setup() {
  Serial.begin(9600);
  DDRB &= 11111110;//set the first bit. you can also write 254
  DDRB ^= (1 << 5);//set the 5th bit by shifting
  PORTB ^= 1;//enable the pull-up
}

void loop() {
  int x = PINB & 1;//store the value of the pin
  if(x == 1){
    delay(10);//optional
    PORTB ^= (1 << 5);
    Serial.println("released");
  }
  else{
    delay(10);//optional
    PORTB &= ~(1 << 5);
    Serial.println("pushed");
  }
}