number="$1" if [[ "$number" =~ "^(2|4|6|8|10|12|14|16|18|20)$" ]]; then echo even elif [[ "$number" =~ "^(1|3|5|7|9|11|13|15|17|19)$" ]]; then echo odd else echo Nan fi
case "$1" in *0|*2|*4|*6|*8) echo even;; *) echo odd;; esac
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