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procedure Decompress(InputFileName, OutputFileName: string);
var
  InputStream, OutputStream : TFileStream;
  DeCompressionStream : TDeCompressionStream;
  a : ^byte;
  i : Integer;
begin
  InputStream := TFileStream.Create(InputFileName, fmOpenRead);
  GetMem(a,655360);
  try
    OutputStream := TFileStream.Create(OutputFileName, fmCreate);
    try
      DecompressionStream := TDecompressionStream.Create(InputStream);
      try
        repeat
          i:=DecompressionStream.Read(a^,655360);
          if i>0 then OutputStream.Write(a^,i);
        until i<655360;
        FreeMem(a);
      finally
        DecompressionStream.Free;
      end;
    finally
      OutputStream.Free;
    end;
  finally
    InputStream.Free;
  end;
end;