diff --git a/2022/ruby/day_20.rb b/2022/ruby/day_20.rb
new file mode 100644
index 0000000..0dbcca7
--- /dev/null
+++ b/2022/ruby/day_20.rb
@@ -0,0 +1,19 @@
+list = ARGF.read.lines(chomp: true).map(&:to_i)
+
+list = list.map { _1 * 811589153 }
+
+list = list.map.with_index { [_2, _1] }
+10.times do
+  (0...list.size).each do |i|
+    j = list.index {|ii,_| ii == i }
+    _, n = list.delete_at(j)
+    j += n
+    j %= list.size
+    list.insert(j, [i, n])
+  end
+end
+
+list = list.map(&:last)
+
+i = list.index(0)
+p [1000, 2000, 3000].sum { list.fetch((i + _1) % list.size) }