diff --git a/15/a3.py b/15/a3.py
new file mode 100644
index 0000000..275125e
--- /dev/null
+++ b/15/a3.py
@@ -0,0 +1,8 @@
+def execute(prog):
+   lines = set()
+   location = 0
+   while True:
+      lines.add(location)
+      if location==len(prog)-1: return "success"
+      location = findLine(prog, prog[location].split()[-1])
+      if location in lines: return "infinite loop"