diff --git a/src/bin/day11.rs b/src/bin/day11.rs
index 1bdb771..d87880c 100644
--- a/src/bin/day11.rs
+++ b/src/bin/day11.rs
@@ -17,6 +17,10 @@ struct Day11 {
 }
 
 impl Day11 {
+    fn count_within(xs: &HashSet<usize>, min_x: usize, max_x: usize) -> usize {
+        xs.iter().filter(|&&x| min_x < x && x < max_x).count()
+    }
+
     fn solve(&self, factor: usize) -> usize {
         let to_add = factor - 1;
 
@@ -31,16 +35,8 @@ impl Day11 {
                         let mut xd = x0.abs_diff(x1);
                         let mut yd = y0.abs_diff(y1);
 
-                        let min_x = min(x0, x1);
-                        let max_x = max(x0, x1);
-
-                        xd += to_add
-                            * self
-                                .empty_xs
-                                .iter()
-                                .filter(|&&x| min_x < x && x < max_x)
-                                .count();
-                        yd += to_add * self.empty_ys.iter().filter(|&&y| y0 < y && y < y1).count();
+                        xd += to_add * Self::count_within(&self.empty_xs, min(x0, x1), max(x0, x1));
+                        yd += to_add * Self::count_within(&self.empty_ys, y0, y1);
 
                         xd + yd
                     })