from PyPDF2 import PdfFileWriter
from PyPDF2 import PdfFileReader

import os
output = PdfFileWriter()
input1 = PdfFileReader(open("Roblox.pdf", "rb"))

# add page 1 from input1 to output document, unchanged
output.addPage(input1.getPage(0))

output.addPage(input1.getPage(3))
output.addPage(input1.getPage(5))


with open("a.pdf","wb") as outputStream:
    output.write(outputStream)
outputStream.close()