int main(int argc, char *argv[])
{
 hextoDec(0xffff);
 return 0;
}

void hextoDec(int hex){
 int sum=0,mul=1;
 int i,r;
 int count=0;
 do{
  r=hex%16;
  for(i=0;i<count;i++)
   mul*=16;
  mul*=r;
  sum+=mul;
  mul=1;
  count++; 
 }while(hex/=16);
 printf("%d\n",sum);
   
}