#/bin/bash
#exercise: Boi Chung

echo -n "input 2 numbers, b >= a: "
read a b

if [ $b -ge $a ]; then
        for ((i=$a; i<=$b; i++ )); do
                if [ $(($i % 7)) -eq 0 ]; then
                    echo -n "abc "
                elif [ $(($i % 13)) -eq 0 ]; then
                    echo -n "xyz "
                elif [ $(($i % 7)) -eq 0 ] && [ $(($i % 13)) -eq 0 ]; then
                    echo -n "abcxyz "
                else
                    echo -n "$i "
                fi
        done
else
        echo "b=$b < a=$a, wrong!"
        exit 1
fi