class IdentityMatrix {
  function : Main(args : String[]) ~ Nil {
    Compress2Range("-6, -3, -2, -1, 0, 1, 3, 4, 5, 7, 8, 9, 10, 11, 14, 15, 17, 18, 19, 20")->PrintLine();

    Compress2Range("0,  1,  2,  4,  6,  7,  8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39")->PrintLine();
  }

  function : Compress2Range(expanded : String) ~ String {
    result := "";
    nums := expanded->ReplaceAll(" ", "")->Split(",");
    firstNum := nums[0]->ToInt();
    rangeSize := 0;
    for(i:= 1; i < nums->Size(); i += 1;) {
      thisNum := nums[i]->ToInt();
            if(thisNum - firstNum - rangeSize = 1) {
                rangeSize += 1;
            }
      else{
        if(rangeSize <> 0){
          result->Append(firstNum);
          result->Append((rangeSize = 1) ? ",": "-");
          result->Append(firstNum+rangeSize);
          result->Append(",");
                    rangeSize := 0;
                }
        else {
          result->Append(firstNum);
          result->Append(",");
        };
        firstNum := thisNum;
      };
    };

    if(rangeSize <> 0){
      result->Append(firstNum);
      result->Append((rangeSize = 1) ? "," : "-");
      result->Append(firstNum + rangeSize);
      rangeSize := 0;
    }
    else {
      result->Append(firstNum);
    };

    return result;
  }
}