字母出现最多 提取 (10091)

C4 右拉 下拉 {=IFERROR(CHAR(SMALL(IF(MIN(LEN(SUBSTITUTE($B4,CHAR(ROW($65:$90)),)))=LEN(SUBSTITUTE($B4,CHAR(ROW($65:$90)),)),ROW($65:$90)),COLUMN(A1)))&D4,"")