#define F_CPU 1000000UL 
#include <avr/io.h>
#include <avr/delay.h>
   
   int main(void) 
   {
   int m = 0;
   int d;
   int x[] = {0b0011,0b0110,0b1100,0b1001};
   
   DDRB = 0x00;
   DDRD = 0xff;  
        while (1) {
			if (PINB==0b01) m = m + 1;
			if (PINB==0b10) m = m - 1;
			
			if (m==4) m = 0; 
			if (m==-1) m = 3;
			
			PORTD = x[m];
			 _delay_ms(20);
		
		}  
   }