#include<reg51.h>
main()
{ unsigned char i,temp,f;
  P0=0xff;
  P1=0x00;
TMOD=0x0D;
   EA=1;
   ET0=1;
   TR0=1;
  while(!P3^3)
  TR0=0;
  temp=TH0*256+TL0;
  while(temp<=500)
  { P0<<1;
    P1++;
	i++;
  }
  f=500000/temp*10^i;

}