I created a program for an unsolveable equation system. My friend somehow forced it to solve the equations. Can you tell me how he did it?

Service: 188.166.133.53:12049

Internetwache CTF 2016 : Remote Printer
Category: Exploit Points: 80 Solves: 101 Description:

Description: Printer are very very important for offices. Especially for remote printing. My boss told me to build a tool for that task.

Attachment: exp80.zip

Service: 188.166.133.53:12377

Internetwache CTF 2016 : FlagStore
Category: Exploit Points: 70 Solves: 211 Description:

Description: Here’s the ultimate flag store. Store and retrieve your flags whenever you want.

Attachment: exp70.zip

Service: 188.166.133.53:12157