void padding ( char ch, int n )
{
  int i;
  for ( i = 0; i < n; i++ )
    putchar ( ch );
}
void structure ( struct drvo *root, int level )
{
  int i;
  if ( root == NULL ) {
    padding ( '\t', level );
    puts ( "~" );
  }
  else {
    structure ( root->desni, level + 1 );
    padding ( '\t', level );
    printf ( "%s\n", root->ime );
    structure ( root->levi, level + 1 );
  }
}