Fix missing check for A at borders

2024/day-4/solution-2.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-paste -s -d '' input.txt | 
+sed 's/^A/B/g;s/A$/B/g' input.txt | paste -s -d '' | 
   perl -lne '
     print "$1$4$2$3" 
     while