diff --git a/version0.9/pda_demo.cpp b/version0.9/pda_demo.cpp
deleted file mode 100644
index be371a9..0000000
--- a/version0.9/pda_demo.cpp
+++ /dev/null
@@ -1,262 +0,0 @@
-#include <list>
-#include <stack>
-#include <cstring>
-#include <iostream>
-
-enum token_type
-{
-	e=1,E,_E,T,_T,F,I,__add,__sub,__mul,__div,__link,__left_curve,__right_curve,sharp
-};
-
-const int max_len=5;
-struct cmp_seq
-{
-	int tokens[max_len];
-	int res;
-};
-cmp_seq par[]=
-{
-	{{T,_E},                        E},
-	{{__add,T,_E},                 _E},
-	{{__sub,T,_E},                 _E},
-	{{__link,T,_E},                _E},
-	{{e},                          _E},
-	{{F,_T},                        T},
-	{{__mul,F,_T},                 _T},
-	{{__div,F,_T},                 _T},
-	{{e},                          _T},
-	{{__left_curve,E,__right_curve},F},
-	{{I},                           F}
-};
-int num_of_par=sizeof(par)/sizeof(cmp_seq);
-
-cmp_seq first_set[]=
-{
-	{{__left_curve,I},E},
-	{{__left_curve,I},T},
-	{{__left_curve,I},F},
-	{{__add,__sub,__link,e},_E},
-	{{__mul,__div,e},_T},
-};
-int num_of_set=sizeof(first_set)/sizeof(cmp_seq);
-
-bool isEnd(int type)
-{
-	return ((type==__left_curve) || (type==__right_curve) || (type==I) || (type==__add) || (type==__sub) || (type==__mul) || (type==__div) || (type==__link) || (type==e) || (type==sharp));
-}
-bool isHead(int head,int type)
-{
-	for(int i=0;i<num_of_set;++i)
-	{
-		if(type==first_set[i].res)
-		{
-			for(int j=0;j<max_len;++j)
-				if(head==first_set[i].tokens[j])
-					return true;
-		}
-	}
-	return false;
-}
-int correct_token_seq(int head,int type)
-{
-	for(int i=0;i<num_of_par;++i)
-	{
-		if((type==par[i].res) && (isHead(head,par[i].tokens[0]) || (head==par[i].tokens[0])))
-			return i;
-	}
-	for(int i=0;i<num_of_par;++i)
-	{
-		if((type==par[i].res) && (par[i].tokens[0]==e))
-			return i;
-	}
-	return -1;
-}
-int place_operator_end(int type)
-{
-	for(int i=0;i<num_of_par;++i)
-	{
-		if((type==par[i].res) && (par[i].tokens[0]==e))
-			return i;
-	}
-	return -1;
-}
-
-
-
-void print_token(int type)
-{
-	std::string str="";
-	switch(type)
-	{
-		case e:
-			str="e";
-			break;
-		case E:
-			str="E";
-			break;
-		case _E:
-			str="E\'";
-			break;
-		case T:
-			str="T";
-			break;
-		case _T:
-			str="T\'";
-			break;
-		case F:
-			str="F";
-			break;
-		case I:
-			str="i";
-			break;
-		case __add:
-			str="+";
-			break;
-		case __sub:
-			str="-";
-			break;
-		case __mul:
-			str="*";
-			break;
-		case __div:
-			str="/";
-			break;
-		case __link:
-			str="~";
-			break;
-		case __left_curve:
-			str="(";
-			break;
-		case __right_curve:
-			str=")";
-			break;
-		case sharp:
-			str="#";
-			break;
-	}
-	std::cout<<str;
-	return;
-}
-
-class PDA
-{
-	private:
-		std::stack<int> main_stack;
-		std::stack<int> comp_stack;
-	public:
-		PDA(std::string& text)
-		{
-			main_stack.push(sharp);
-			for(int i=(int)text.length()-1;i>=0;--i)
-			{
-				if(text[i]=='(')
-					main_stack.push(__left_curve);
-				else if(text[i]==')')
-					main_stack.push(__right_curve);
-				else if(text[i]=='i')
-					main_stack.push(I);
-				else if(text[i]=='+')
-					main_stack.push(__add);
-				else if(text[i]=='-')
-					main_stack.push(__sub);
-				else if(text[i]=='*')
-					main_stack.push(__mul);
-				else if(text[i]=='/')
-					main_stack.push(__div);
-				else if(text[i]=='~')
-					main_stack.push(__link);
-			}
-			comp_stack.push(sharp);
-			comp_stack.push(E);
-		}
-		void print_stack(std::stack<int>& temp)
-		{
-			std::stack<int> t;
-			while(!temp.empty())
-			{
-				t.push(temp.top());
-				print_token(t.top());
-				temp.pop();
-			}
-			while(!t.empty())
-			{
-				temp.push(t.top());
-				t.pop();
-			}
-			return;
-		}
-		void print_main_and_comp()
-		{
-			print_stack(main_stack);
-			std::cout<<"		";
-			print_stack(comp_stack);
-			std::cout<<std::endl;
-			return;
-		}
-		void work()
-		{
-			print_main_and_comp();
-			while((main_stack.top()!=sharp) || (comp_stack.top()!=sharp))
-			{
-				if(!isEnd(comp_stack.top()))
-				{
-					if(isHead(main_stack.top(),comp_stack.top()))
-					{
-						int i=correct_token_seq(main_stack.top(),comp_stack.top());
-						comp_stack.pop();
-						for(int j=max_len-1;j>=0;--j)
-							if(par[i].tokens[j])
-								comp_stack.push(par[i].tokens[j]);
-					}
-					else if(!isHead(main_stack.top(),comp_stack.top()))
-					{
-						//to check if this can be extended as 'e'
-						int i=place_operator_end(comp_stack.top());
-						if(i!=-1)
-							comp_stack.pop();
-						else
-						{
-							std::cout<<"error."<<std::endl;
-							return;
-						}
-					}
-					else
-					{
-						std::cout<<"error."<<std::endl;
-						return;
-					}
-					print_main_and_comp();
-				}
-				else
-				{
-					if(main_stack.top()==comp_stack.top())
-					{
-						main_stack.pop();
-						comp_stack.pop();
-					}
-					else if(comp_stack.top()==e)
-						comp_stack.pop();
-					else
-					{
-						std::cout<<"error."<<std::endl;
-						return;
-					}
-					print_main_and_comp();
-				}
-			}
-			std::cout<<"accept."<<std::endl;
-			return;
-		}
-};
-
-int main()
-{
-	std::string text;
-	while(1)
-	{
-		std::cin>>text;
-		PDA m(text);
-		m.work();
-	}
-	return 0;
-}