1 files changed, 3 insertions, 0 deletions
diff --git a/input.lisp b/input.lisp
index dcea8f6..4edf6aa 100644
--- a/input.lisp
+++ b/input.lisp
@@ -25,6 +25,9 @@
                  :file (file input)
                  :cursor (+ (cursor input) amount)))
 
+(defun input-sub (input1 input2)
+  (- (cursor input1) (cursor input2)))
+
 (defun from-string (str)
   (make-instance 'input :data str))