The title of the challenge, angrme was a big clue as to what is expected: use the angr framework to solve it!
Running the binary with some random input makes it print
:(. A quick look at the binary in IDA shows a lot of comparisons; if any of them fails, it will output
:(, and if they are all successful, it will output
:). So, we need to tell angr to symbolically execute until it reaches the basic block which outputs