removed useless imports

2/main.ml

@@ -1,5 +1,4 @@
 open Printf;;
-open String;;
 
 let rec list_of_lines in_file =
   try
@@ -15,7 +14,7 @@ let is_not_empty lst =
   | _  -> true
 
 let rec parse_int_list 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
   List.map int_of_string list1
 
 let rec int_list_diff int_list =