struct Node
{
  std::string name;
  std::vector<Node*> children;
};

char c;
Node* root = new Node();
root->name = "dummy";
std::stack<Node*> nodeStack;
nodeStack.push(root);

int depth =  1 ;
int symbol_ok = false;

while( (c = std::cin.get()) != EOF)
{
  if (c == '\n')
  {
    depth =  1 ;
    symbol_ok = false;  
  }
  else if (c == '\t')
  {
    if (!symbol_ok)
      depth++;
    else
      nodeStack.top()->name += c;
  }  
  else
  {
    if (stack.size() +  1  < depth)
      throw  1 ; // bad file format
    while (stack.size() >= depth)
      stack.pop();
    Node* nd = new Node();
    stack.top()->children.push_back(nd);
    stack.push(nd);
  }
}