read start end

n=$start
while [ "$n" -le "$end" ]
do
  if [ $((n % 3)) -eq 0 ]; then
    echo "$n"
  else
    echo "$n" | grep -q '3'
    if [ $? -eq 0 ]; then
      echo "$n"
    fi
  fi
  n=$((n+1))  
done