foreach ($computer in (Get-Content C:appsdatabase-1.csv)) {
  try{
    $test = Get-ADComputer -Identity $computer -ErrorAction Stop
    if($test){
     Write-Output "$computer" | Out-File C:appsexist.csv -Append
    }
 }catch{
   Write-Output "$computer" | Out-File C:appsNonexist.csv -Append
 }
}