function GetA1([int] $n) {
    if($n -gt 26){
        $divs=[Math]::Truncate($n / 26)
        $C1= [System.Convert]::ToChar([int]$divs+64)
        if($C1 -eq "@"){$C1="Z"}
        　$rest=$n % 26
       　 $C2= [System.Convert]::ToChar($rest+64)
        if($C2 -eq "@"){$C2="Z"}
        　$A1=$C1+$C2
        return $A1
    }else{
         $rest=$n % 26
         $C1= [System.Convert]::ToChar($rest+64)
         if($C1 -eq "@"){$C1="Z"}
         　return $C1
    }
}