string chartype = project.Variables["Type"].Value
Charset charset;

if(chartype == "a")
    charset = Charset.LettersAndNumbers;
if(chartype == "b")
    charset = Charset.OnlyLetters;
if(chartype == "c")
    charset = Charset.OnlyNumbers;

var results = Permutation.Work(
    project.Variables["SerialKey"].Value,
    Int32.Parse(project.Variables["CountCharacters"].Value),
    Int32.Parse(project.Variables["MaxKey"].Value),
    charset
);

foreach(var item in results)
{
  project.SendInfoToLog("[-]" + item, false);
}