Where did you get "28"?

Code:

for string in "Komendant st. house 50 ex. 1 fl. 1000" \
              "Elsestreet house 51 ex. 2 fl. 11"
do
  a=${string%"${string#????}"} ## put first four characters in $a

  set -f
  set -- $string
  set +f
  shift $(( $# - 5 ))

  echo $a.$1.$3.$5
done