#include <avr/io.h>

#define LedPin 4
#define SwitchPin 3

void setup() {
  DDRB &= ~(1<<SwitchPin);    //set switchPin as input
  DDRB |= (1<<LedPin);        //set ledPin as output
  
}
void loop() {
  if (PINB &(1<<SwitchPin)){   //check if switch ON
    PORTB |= (1<<LedPin);      //Turn Led ON
  }
  else {
    PORTB &= ~(1<<LedPin);     //Turn Led Off
  }

}