diff --git a/.gitignore b/.gitignore
index 1745385..64b782f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,7 @@
 initcon
-bac
 .idea
 *.json
+*.jsonl
 *.bin
 super.in
 __pycache__/
diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..569e485
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "bac"]
+	path = bac
+	url = https://git.lw1.at/lw1/collision-interpolation.git
diff --git a/bac b/bac
new file mode 160000
index 0000000..5e55a18
--- /dev/null
+++ b/bac
@@ -0,0 +1 @@
+Subproject commit 5e55a18b99bb43150cb05daf49cba6f806c94143