removed useless imports

1/main.ml

@@ -1,5 +1,4 @@
 open Printf;;
-open String;;
 
 let rec build_list in_file =
   try
@@ -15,7 +14,7 @@ let is_not_empty lst =
   | _  -> true
 
 let rec parse_list (l1, l2) str =
-  let list1 = (List.filter (fun a -> length a != 0) (String.split_on_char ' ' str)) in
+  let list1 = (List.filter (fun a -> String.length a != 0) (String.split_on_char ' ' str)) in
   let list_of_int = List.map int_of_string list1 in
   match list_of_int with
   | e1 :: e2 :: _ -> (e1 :: l1, e2 :: l2)