#include "avr/io.h"
int main ( )
{
	DDRB |= (1<<3);	
	while (1)
	{
		OCR0 = 99;		
		TCCR0 = 0x19;    
		while ((TIFR&(1<<OCF0)) == 0);
		TIFR = (1<<OCF0);
		OCR0 = 69;		
		TCCR0 = 0x39;	 
		while ((TIFR&(1<<OCF0)) == 0);
		TIFR = (1<<OCF0);	
	}
	return 0;
}