diff --git a/Makefile b/Makefile
index a7a56ce735b0b62188201a5be4da5d6742cfebe8..29010e5b85265e2b7522402e2cc6b90a312232a8 100644
--- a/Makefile
+++ b/Makefile
@@ -15,11 +15,12 @@ tests: $(OSRC) tests.ml
 	./tests
 
 circuits: $(OSRC) circuits.ml
+	mkdir -p graphics
 	$(OCAMLCC) -g -o circuits $(OSRC) circuits.ml
 	./circuits
 
 clean:
 	rm *.cmi
 	rm *.cmo
-	rm *.pdf
-	rm *.dot
+	rm graphics/*.pdf
+	rm graphics/*.dot
diff --git a/README.md b/README.md
index 6892fd187faaa9c11bcb7d7e7c512b7ae6c6a438..4de52e5517f6ae3875f2ba44038f7575ae78a557 100644
--- a/README.md
+++ b/README.md
@@ -24,13 +24,22 @@ To compile and run the circuits
 make circuits 
 ```
 
+Once it is built, you will be able to use it with the following 
+console command :
 
-To update your version of the repository 
+```
+./circuits
+```
+
+Note that the default circuit is obtained by reading `lines.txt`, 
+but any alternative text file can be used by supplying the filename 
+as an argument :
 
 ```
-git pull origin master
+./circuits filename
 ```
 
+The graphics are generated in a separate directory called `graphics`.
 
 
 ## Syntax overview 
diff --git a/circuits.ml b/circuits.ml
index fa4b965d164745e8fe52af58c36f1d7c1250894b..408bd57119363596edf9abe9829fe2d632e7d819 100644
--- a/circuits.ml
+++ b/circuits.ml
@@ -158,9 +158,10 @@ let convert_label = function
 
 let ptg_of_dag dag = 
     
-    (*Dags.debug_dag dag;*)
+    (* Dags.debug_dag dag; *)
 
-    (* FIRST OF ALL TRANSLATE ALL THE NAMES SO THAT
+    (* 
+     * FIRST OF ALL TRANSLATE ALL THE NAMES SO THAT
      * THEY DO NOT CONFLICT WITH OTHER PTG NAMES
      *)
     let dag    = mapids (fun x -> x + !counter) dag in 
@@ -278,7 +279,7 @@ let fc = ref 0;;
  *)
 let report txt ptg = 
     incr fc;
-    let base = Printf.sprintf "test%03d" !fc in 
+    let base = Printf.sprintf "graphics/test%03d" !fc in 
     (*print_string (txt ^ ": " ^ base ^ "\n");*)
     (*ptg |> string_of_ptg |> print_string ;*)
     ptg_to_file (base ^ ".dot") ptg;