1 files changed, 23 insertions, 0 deletions
diff --git a/challenge-121/abigail/lua/ch-1.lua b/challenge-121/abigail/lua/ch-1.lua
new file mode 100644
index 0000000000..52b7529007
--- /dev/null
+++ b/challenge-121/abigail/lua/ch-1.lua
@@ -0,0 +1,23 @@
+#!/opt/local/bin/lua
+
+--
+-- See ../README.md
+--
+
+--
+-- Run as: lua ch-1.lua < input-file
+--
+
+for line in io . lines () do
+    _, _, m, n = line : find ("(%d+)%s+(%d+)")
+    x = 1
+    for i = 1, n - 1 do
+        x = x * 2
+    end
+    if   math . floor (m / x) % 2 == 1 then
+        m = m - x
+    else
+        m = m + x
+    end
+    print (m)
+end