=if(A1=S1,11,IF(A1=S2,12,"既不等于S1,也不等于S2"))
b1=if(a1="s1",11,if(a1="s2",12,""))
=HLOOKUP(A1,{"S1","S2";11,12},2,0)
=10+match(A1,S:S,0)