單一字母 提取 (13043)

F2{=INDIRECT(TEXT(SMALL(IF(COUNTIF(A:D,A$2:D$12)=1,ROW($2:$12)*10+{1,2,3,4},999),ROW(A1)),"!R0C0"),)&""

A2:D12格式化=COUNTIF($A:$D,A2)=1