Router + router on one adsl line, possible?

HI there, greetings from Croatia! I need some help here. I this possible (picture)? If it is, where I have to input LAN cable from Thompson router to Siemens router? Here is the problem: In my home there is 3 PC, 2 laptops, 4 mobphones. They are all on Thomson, LAN or WiFi, everything is working fine. But.. Yesterday I manage to repair older PC (PC2 on the picture) for daughter, and...