diff --git a/Slist.c b/Slist.c
index f5571c8..f2d58ed 100644
--- a/Slist.c
+++ b/Slist.c
@@ -1 +1,46 @@
 #include "Slist.h"
+
+List make_empty_list(){
+  return NULL;
+}
+
+int is_empty(List l){
+  return l==NULL;
+}
+int isIn_List(List l, char e){
+  return !is_empty(l) &&
+    (isIn_tree(l.letter,e) ||
+     isIn_list(l.next,e));
+}
+
+
+//add
+void addHead(List*l,char e){
+  cell* tmp=malloc(sizeof(cell));
+  tmp->letter=make_tree(e);
+  tmp->next=*l;
+  *l=tmp;
+}
+void addNext(List*l,char e){
+  if(is_empty(*l))
+    addHead(l,e);
+  else{
+    cell* tmp=malloc(sizeof(cell));
+    tmp->letter=make_tree(e);
+    tmp->next=*l->next;
+    *l=tmp;
+}
+void addAlpha(List*l,char e){
+  if(is_empty(*l) || e<(l->letter->val)){
+    addHead(l,e);
+    return;
+  }
+  cell* crt=*l;
+  while(!is_empty(crt->next) && e < crt->next->letter->val)
+    crt=crt->next;
+  if(is_empty(crt->next))
+    addHead(&crt->next,e);
+
+  if(e> crt->next-letter->val){
+    
+}
diff --git a/Slist.h b/Slist.h
index 6f15421..6467490 100644
--- a/Slist.h
+++ b/Slist.h
@@ -14,9 +14,10 @@ typedef
 //function
 List* make_empty_List();
 int is_empty(List);
-tree* head(List);
-List* Queue(List);
-
+int isIn_list(List,char);
+void addAlpha(List*,char);
+void addHead(List*,char);
+void addNext(List*,char);
 
 
 
diff --git a/tree.c b/tree.c
index bc9531c..456cc83 100644
--- a/tree.c
+++ b/tree.c
@@ -1 +1,15 @@
 #include "tree.h"
+
+tree make_empty_tree(){
+  return NULL;
+}
+int is_empty(tree t){
+  return t==NULL;
+}
+int is_leaf(tree t){
+  return is_empty(t.next);//<=>t.val=='\0'
+}
+int is_end(tree t){
+  return isIn_list(t.next,'\0');
+}
+
diff --git a/tree.h b/tree.h
index f3c4236..ecb7c53 100644
--- a/tree.h
+++ b/tree.h
@@ -15,17 +15,21 @@ typedef
 
 
 //functions
-tree* make_empty_tree();
+tree make_empty_tree();
+tree make_tree(char);
+int is_empty(tree);
+int is_leaf(tree);
+int is_end(tree);
 tree* cons_tree();
 tree* load_tree(FILE*,tree*);
-int is_empty(tree);
-char value(tree);
 //char*? values(tree);
 void print_all(tree);
-int isIn(tree,string);
-
-
+int isIn_tree(tree,char);
+int strIsIn_tree(tree,string);
 
 
+/*
+words end with '\0' and 
+*/
 
 #endif //TREE_H
--
libgit2 0.21.2