void main()
{
trisa.f0=1;trisb=0;portb=0;
loop:
if(porta.f0==0)
              {portb=3;delay_ms(1000);
               portb=5;delay_ms(1000);
               while(porta.f0==0){}
               while(porta.f0==1){}
               portb=0;
               while(porta.f0==0){}
               }
goto loop;
}