18 - tzādi
צ is pronounced /tz/:
צד (side) עצוב (sad)
צ׳ (with an apostrophe) is pronounced as the ch in "Charlie", and is used in words of foreign origin:
צ׳רצ׳יל (Churchill)
Next
א ב ג ד ה ו ז ח ט י כ ך ל מ ם נ ן ס ע פ ף צ ץ ק ר ש ת