- { [ 2dup length 1- number= ] [ 2drop 4 ] }
- { [ 2dup [ 1- ] dip nth Letter? not ] [ 2drop 10 ] }
- { [ 2dup [ 1+ ] dip nth Letter? not ] [ 2drop 4 ] }
+ { [ 2dup length 1 - number= ] [ 2drop 4 ] }
+ { [ 2dup [ 1 - ] dip nth Letter? not ] [ 2drop 10 ] }
+ { [ 2dup [ 1 + ] dip nth Letter? not ] [ 2drop 4 ] }