Prepare remaining days.

2020/src/day20.rs

@@ -0,0 +1,12 @@
+use std::io::Read;
+
+use crate::Solution;
+
+#[derive(Default)]
+pub struct Day20;
+
+impl Solution for Day20 {
+    fn part1(&mut self, _input: &mut dyn Read) -> String {
+        todo!()
+    }
+}