diff --git a/.gitignore b/.gitignore
index b24d71e..6aea462 100644
--- a/.gitignore
+++ b/.gitignore
@@ -48,3 +48,7 @@ Thumbs.db
 *.mov
 *.wmv
 
+# C files
+builds/
+Colleen
+Grace
diff --git a/1_Colleen/Colleen b/1_Colleen/Colleen
deleted file mode 100755
index ddf6173..0000000
Binary files a/1_Colleen/Colleen and /dev/null differ
diff --git a/1_Colleen/builds/Colleen.o b/1_Colleen/builds/Colleen.o
deleted file mode 100644
index 510ff48..0000000
Binary files a/1_Colleen/builds/Colleen.o and /dev/null differ
diff --git a/2_Grace/Grace b/2_Grace/Grace
deleted file mode 100755
index 994a32a..0000000
Binary files a/2_Grace/Grace and /dev/null differ
diff --git a/2_Grace/Grace.c b/2_Grace/Grace.c
index 70b4936..eb53d15 100644
--- a/2_Grace/Grace.c
+++ b/2_Grace/Grace.c
@@ -1,13 +1,14 @@
 /*comment outside*/
 #include <stdio.h>
+#define not_main main
 
 char *second_function() {
-	return "/*comment outside*/%c#include <stdio.h>%c%cchar *second_function() {%c	return %c%s%c;%c}%c%cint main() {%c	/*comment inside*/%c	char *program = second_function();%c	printf(program, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);%c	return 0;%c}%c";
+	return "/*comment outside*/%c#include <stdio.h>%c#define not_main main%c%cchar *second_function() {%c	return %c%s%c;%c}%c%cint not_main() {%c	/*comment inside*/%c	char *program = second_function();%c	printf(program, 10, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);%c	return 0;%c}%c";
 }
 
-int main() {
+int not_main() {
 	/*comment inside*/
 	char *program = second_function();
-	printf(program, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);
+	printf(program, 10, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);
 	return 0;
 }
diff --git a/2_Grace/builds/Grace.o b/2_Grace/builds/Grace.o
deleted file mode 100644
index 3ac5ab0..0000000
Binary files a/2_Grace/builds/Grace.o and /dev/null differ
diff --git a/2_Grace/tmp_Grace.c b/2_Grace/tmp_Grace.c
new file mode 100644
index 0000000..eb53d15
--- /dev/null
+++ b/2_Grace/tmp_Grace.c
@@ -0,0 +1,14 @@
+/*comment outside*/
+#include <stdio.h>
+#define not_main main
+
+char *second_function() {
+	return "/*comment outside*/%c#include <stdio.h>%c#define not_main main%c%cchar *second_function() {%c	return %c%s%c;%c}%c%cint not_main() {%c	/*comment inside*/%c	char *program = second_function();%c	printf(program, 10, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);%c	return 0;%c}%c";
+}
+
+int not_main() {
+	/*comment inside*/
+	char *program = second_function();
+	printf(program, 10, 10, 10, 10, 10, 34, program, 34, 10, 10, 10, 10, 10, 10, 10, 10, 10);
+	return 0;
+}
diff --git a/MakefileCommon b/MakefileCommon
index 81611e5..4905ff8 100644
--- a/MakefileCommon
+++ b/MakefileCommon
@@ -55,6 +55,7 @@ ifeq "$(D_OBJS)" "."
 else
   RM_OBJS     = rm -rf $(D_OBJS)
 endif
+F_DIFF        = tmp_$(NAME).c
 
 
 # - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - #
@@ -88,12 +89,15 @@ $(NAME): $(OBJS)
 leaks: $(NAME)
 	valgrind --leak-check=full --show-leak-kinds=all ./$(NAME)
 
-diff: $(NAME)
+diff_clean:
+	rm $(F_DIFF)
+diff_exec:
 	@echo $(CYAN)"compare source with output :"$(RESET)
-	./$(NAME) > tmp_$(NAME)
-	- diff --color tmp_$(NAME) $(SRCS); \
+	./$(NAME) > $(F_DIFF)
+	- diff --color $(F_DIFF) $(SRCS); \
 		if [  $$? -eq 0 ]; then echo $(GREEN)"Files $(NAME) and $(SRCS) are identical"$(RESET); else echo $(RED)":Files $(NAME) and $(SRCS) differ"$(RESET); fi
-	rm tmp_$(NAME)
+diff: $(NAME) diff_exec diff_clean
+diff_keep: $(NAME) diff_exec
 
 clean:
 	$(RM_OBJS)